Pinephone won't boot.

[fxc]

Pinephone screen stopped working. The system starts but the screen is black. When starting the jumpdrive, the screen is bright gray, but after an hour of charging, nothing has changed. The battery voltage is 3.76 volts. I have tried different operating systems and chargers. The last time it worked, I turned it off by holding the power button and put it on the table.

Which Jumpdrive image did you flash? Jumpdrive is not supposed to show a gray screen, instead it should show this screen: https://wiki.pine64.org/images/1/1a/Jumpdrive.jpg

The rest of the symptoms describe a drained battery, maybe beyond the point of saving. Mind that in this state, charging it for only one hour in Jumpdrive is not sufficient, at this state it will charge very slowly and it is required to charge it multiple hours until the drained battery takes some charge again.