It sounds like the Apple TVs lost their Wi-Fi connection while still locked in Single App Mode, which is a common issue when configuration profiles change. Unfortunately, when they’re in this state or unmanaged, remote fixes usually won’t work because the devices can’t talk to your MDM.

Here are a few options you can suggest:

1. Physical Reset via Recovery Mode
   For Wi-Fi-only Apple TVs without USB or Ethernet, you can force a factory reset by power-cycling the device five times in succession. Let it fully boot each time before unplugging again. After the fifth cycle, you should see a “Recovery Mode” screen with an option to reset all settings. This will wipe the device and allow you to re-enrol it in MDM.

2. Apple Configurator (if possible)
   If you can connect the Apple TV to a Mac (some models allow this via USB-C), you can use Apple Configurator 2 to remove Single App Mode. In Configurator, right-click the device, go to Advanced, and select Stop Single App Mode.

3. Preventative Tip for Next Time
   Before pushing profile changes, consider temporarily disabling Single App Mode or ensuring the new profile includes valid Wi-Fi credentials. This avoids devices getting stuck offline.

Is it the model with or without a USB port on the back?  We have a few without the USB port that are kinda bricked as well.  Supposedly if you plug and unplug them from power 5 times fast (I know, it goes against all instinct) they will reset to factory, but we have not seen that with the ones we have.

I think you need to physically connect each Apple TV to a Mac using Apple Configurator and remove/reset the configuration profile. Without a network connection, they can’t receive updated profiles remotely.

Any chance these are the ones with the network port?  I mean, that’s the go to in order to get them to connect to update the config profiles.  Otherwise direct connection to AC2 and wiping them would be the way forward as others have said.