i am having similar issues and i feel its a hardware issue for the A series when they start getting worked up I added extra heat insulators for the motherboard and the device didn't restart since morning till I tried cloning the device then it started freezing and did the same thing
Have you tried force restarting the device? since it didn't fall or gradually fade off it could just be a software issue that can be fixed with restarting, if that doesn't work then you can try the hardware fix according to oldturkey03
