My phones being weird.

90% of the time when I turn it on, it appears to boot up, but the screen remains black, on the odd occasion I can see the Nokia logo, the phone boots up to the lock code/PIN code entry screen but after a couple of seconds of reaching my desktop, the screen goes black again.

Another thing, when you power on the phone it vibrates for a brief seconds, right? But it's not doing that any more, the white light comes on but no vibrate.

It was working fine this morning, the battery died at an almost full charge later in the day which I thought was strange but just put down to another one of the N900s features.

I've tried reflashing the rootfs, but this hasn't helped.
I would put it down the a brightness issue in the settings but that wouldn't explain why I can see the Nokia logo 10% of the time when it boots and the lock code screen.

Any tips?