# Getting a screen back by itself after a power cut > Three separate things have to go right before a board comes back on its own: the panel takes power, the player comes to the front, and the network returns. Only the middle one is ours. Here is how to set up all three and how to test it in ten minutes. Source: https://channelos.tv/academy/after-a-power-cut Published: 2026-10-29 Track: When it goes wrong Lesson 3 of 4 Plan: Free plan Time: about 10 minutes Author: The ChannelOS team **A screen comes back by itself when three things go right: the panel takes power and switches on, the player comes to the front, and the network is back so the board can load. Set the TV to resume its last power state or put a plug timer on it, then install the Android TV app and make it the home app with kiosk mode. Start after a power cut is best effort, not a guarantee.** --- ## The short version, in 6 steps 1. Pull the plug at the wall, wait ten seconds, plug it back in and watch what the TV does on its own. 2. In the TV's own settings, find the power or startup section and set it to resume the last state or to power on. 3. If there is no such setting, fit a plug timer or smart plug so the set gets mains power at the hour you open. 4. On the TV, install the ChannelOS Android TV app from channelos.tv/tv.apk and pair the screen. 5. In the app's remote menu turn on Start when the TV powers on, then turn on Kiosk mode and choose ChannelOS in the television's own home app picker. 6. Cut the power again and leave the remote on the counter until the board comes back. --- The outage is not the part that costs you. Four minutes at two in the morning, nobody in the building, and by breakfast the electricity company has forgotten about it. The cost is everything after, because a stopped screen does not announce itself. A dark TV looks exactly like a TV somebody switched off on purpose, and a set sitting on its home screen looks like somebody was using it. **Three things have to go right before a board comes back on its own, and only the middle one is ours.** The panel has to take power and switch itself on. The player has to come to the front without anyone pressing a button. And the network has to be back, because the board is fetched fresh every time a screen starts. Work through them in that order. Three different owners, three different fixes, and skipping to the software half leaves a screen that still needs visiting. ## Why does my TV not come back after a power cut? Because a television that loses power does not resume, it decides, and which decision depends on the set. There are three behaviours to tell apart: it returns to the state it was in when the power went, it comes back in standby and waits for the remote, or it powers on but lands on its own home screen rather than whatever was open. None of that is a signage setting and no software anywhere can override it. It is hardware behaviour chosen by the manufacturer, so it is the first thing to establish about your own panel: it decides whether anything else here is worth doing. The test at the end of this lesson tells you which sort yours is. ## How do I make the TV turn on automatically? Two routes, and which one you need depends on what your own panel does when the power comes back. **Route one is the set's own setting.** Look in the television's settings for a group called Power, Startup, Eco or General, and an option named something close to **Power on state**, **Last state**, **Auto power on** or **Boot setting**. Set it to resume the last state. The wording moves around by manufacturer and model year, so no page can give you the exact menu path. The manual can. **Route two is a plug timer or a smart plug.** It gives the set mains power at the hour you open and cuts it at the hour you close. On a panel that returns to its last state that alone is a complete answer, and it is the same device doing the other half of this job from the other end, which is [turning the screen off when nobody is in the room](/academy/run-a-screen-24-7). One catch before you buy anything: on a set that always comes back in standby, mains power is not enough and somebody still presses a button. If a streaming stick drives the screen, check HDMI-CEC first. That is the standard that lets a device coming out of standby tell the television to switch on and change to its input. Every manufacturer files it under a different name, and the plug test tells you whether yours has it on. ## How do I make a TV open an app on startup? This is where a browser tab stops being enough. A tab left open at the player address survives a dropped wifi connection perfectly well. It does not survive a cold boot: the television restarts, the browser closes with it, and there is nothing in a web page that can reopen a web page. The Android TV app exists for that one job. It is not on Google Play yet, so it is a direct download from our own site: type `channelos.tv/tv.apk` on the TV, Android 8.0 or newer, with the steps on [the Android TV app page](/android-tv-digital-signage). The board is identical either way. This is not a better player, it is a shell that can be told to start. Two settings in its remote menu matter here, and they are not the same promise. **Start when the TV powers on** listens for the television's boot signal and opens the board. It is on by default and it is **best effort**, because Android restricts apps that start themselves and TV makers enforce that differently; nobody can tell you in advance which sort your set is. **Kiosk mode (use as TV home app)** is the one that holds. ## What is kiosk mode on Android TV? In our app it means one specific thing: the toggle makes the app **eligible** to be the television's home app, then hands you to the **TV's own home app picker** to choose ChannelOS yourself. After that the set opens the board whenever it starts, because a television always launches its home app. That is why it holds where boot start does not. It is not a lock on your TV. No lock task mode, no screen pinning, no device owner enrolment, no provisioning code. The same toggle reverses it and the television's own picker always wins. ## What happens if the internet is not back yet? The screen waits, and this is the layer we genuinely cannot fix for you. What a screen shows is worked out from the show and the channel in real time, which is why an edit reaches every screen tuned to it with no re-publish step. The other side of that: the page and the show are fetched fresh every time a screen starts. A board already playing rides out a wifi drop on the copies in the browser's own storage. A board starting from nothing has nothing to fall back on. A screen can finish starting before the line is back, because the router has its own boot sequence first. The app covers that stretch with nobody there: it backs off, retries, and reloads the moment the network returns. [What happens when the wifi drops](/academy/when-the-wifi-drops) is worth reading before you blame the TV for something the line did. ## How do I test it without waiting for a power cut? Ten minutes, at the wall, with the shop shut. 1. **Put a real board on the screen.** The first screen is free for ever, so this costs nothing. A free screen carries a ChannelOS banner along the bottom, and about every 2 minutes that banner opens into a full ChannelOS slide for roughly 30 seconds naming what ChannelOS is and the channelos.tv address, then folds back. Any paid plan removes both. 2. **Set the two toggles.** Open the app's remote menu, check **Start when the TV powers on** is on, then turn on **Kiosk mode** and pick ChannelOS in the television's home app picker when it appears. 3. **Pull the plug at the wall.** Not standby, not the remote. The socket. 4. **Wait ten seconds and plug it back in.** Put the remote down and leave it. 5. **Watch where it stops.** Still dark is layer one. On its own home screen is layer two. A retry message is layer three, and that one usually sorts itself out. Whatever it does on a Tuesday afternoon with you watching is what it will do at six in the morning with nobody there. ## When this is the wrong answer **If the screen has to be running at a fixed hour with nobody on site, buy a media player.** That is what a hardened player with local storage is sold for: it holds its own copy, starts from that copy, and does not care whether the line is back. We do not do that, and if a missed morning costs you money, [a player box](/blog/digital-signage-player-do-you-need-one) is money well spent somewhere else. **If the site loses power often, the fix is upstream of all three layers.** A small UPS under the router and the screen keeps both powered through a short cut, so nothing reboots and none of the three layers above is tested at all. For a shop where somebody unlocks the door anyway, none of that applies. A plug timer, the app set as the home app, and the board is up before the first customer is in, with nobody looking for a remote. Pull the plug on your own screen this evening and time what happens. You will know within a minute which of the three layers needs fixing, and two of the three are a ten minute job. ## Frequently asked questions ### How do I make my TV turn on automatically? Two routes. Many sets have an option under Power, Startup or General called something like Power on state, Last state or Auto power on, and setting it to resume the last state is enough on its own. Where no such option exists, a plug timer or smart plug gives the set mains power at the hour you open. Which route works depends on whether your panel returns to its last state or always comes back in standby, and the only way to know is to pull the plug and watch. ### How do I make a TV open an app on startup? On Android TV and Google TV, install the app and make it the television's home app. The system always launches its home app when it starts, so the board opens without anyone pressing a button. In the ChannelOS app that is the Kiosk mode toggle in the remote menu, which makes the app eligible and then sends you to the TV's own home app picker to choose it. A browser tab cannot do this: a tab is closed by the reboot and nothing reopens it. ### What is kiosk mode on Android TV? In our app it means one thing only: the app becomes eligible to be the television's home app, and you then pick it yourself in the TV's own picker. After that the set opens the board when it starts. There is no lock task mode, no screen pinning, no device owner enrolment and no provisioning code. The same toggle reverses it, and the television's own picker always wins, so nothing here can hold a TV against its owner. ### Will my digital sign come back after a power cut? With the TV set to power on and the Android TV app installed as the home app, usually yes, with no one in the room. It is best effort rather than a guarantee, because Android restricts apps that start themselves and manufacturers enforce that differently. It also needs the network back, since the page and the show are fetched fresh every time a screen starts. If a screen must be up at a fixed hour with nobody on site, buy a media player with local storage. ### Does the browser tab survive a reboot? No. A tab open at the player address keeps playing through a dropped wifi connection, because the show's pictures and clips are already held in the browser's own storage. A cold boot is different: the television restarts, the browser is closed with it, and nothing reopens the tab. That is the single job the native Android TV app exists to do, and it is the reason to install it on a screen nobody wants to walk over to. ## Next lesson [The show and the screen are different shapes](https://channelos.tv/academy/show-and-screen-different-shapes) ## Further reading - https://channelos.tv/blog/android-tv-digital-signage-app - https://channelos.tv/blog/digital-signage-player-do-you-need-one - https://channelos.tv/android-tv-digital-signage The whole curriculum: https://channelos.tv/academy and https://channelos.tv/academy.md