@joerg_rw no I'm using my n810 to charge. That's not the problem. The PC detects it as mass storage. Doesn't charge from adapter, or at most the indicator goes yellow, the phone vibes, and 'pulses' yellow a couple of times, even though I've switched that indicator off.

Seems to almost be like a Apple MacBook SMC issue that 'appears' when you left the battery bloat and die.

The usb could well be on the way out. 2 of the 4 suffered that problem.

One really odd thing. It retains the date and time now, when left without a battery for hours.