TiggyTheTerrible If it fried my phone, it wasn't free.
You are still acting as if this is caused by the OS.
It likely isn't.
TiggyTheTerrible I reset it. And now I'm back to square one and it won't power on at all.
And that's the proof right here. The OS, as I've stated before, only comes into play when the device has booted. It has nothing to do with the firmware. You should be able to power on the phone and get into fastboot 100% of the time, if the hardware itself doesn't have any defects.
And that seems like a possibility now.
Before you get a go at this option: no, GrapheneOS can't and didn't damage your hardware.