Re: New N900 Battery; Need UK supplier
 

Thanks @dr_frost_dk and @kaos_king.

I updated the software using the Nokia NSU tool rather than Maemo Flasher, which for some reason wouldn't work (possibly because I was using a cheap non-Nokia USB cable?)

Device seems to be working okay again now. I can use WiFi and battery life seems to be back to normal. Never could figure out what caused it.