Chosen Solution
I was play The dying of light, suddenly FPS goes 12 from 60. I found the top fan has no wind and sound, the console temperature abnormally high. I realized maybe the fan not working for unknown reason. So I try to restart the console. Then I found I can enter BIOS, but if I select steamOS the screen stoped at the Logo of steamdeck, after around 5min the screen turns black and has no responding. I do not use any third party accessories.
Sounds like a bad fan to me and it may be overheating so it automatically shuts off during the boot process. What I would do is remove the back cover and check for fan spin. If the fan is not spinning I would use the Steam Deck Fan Replacement Guide and get a new Steam Deck Fan and replace it.
