Latitude d630 -- accidentally dimmed screen during safe mode startup

First of all, running XP but my laptop recently thinks it's an expired, unregistered version. So I've been running it in safe mode until I can get it looked at.

I was pressing f8 during start up and was accidentally resting my wrist on the arrow keys (which also control brightness, I'm assuming) Now the screen lights up a bit but I can't see anything that's happening. If I press enter I can still log in and it makes all the login noises. So it's not the laptop that's failing. Fn + f8 + the up and down arrows will dim or brighten, but I still can't see anything.

I did this once before and started it without the battery in it and it worked perfect after that. So the monitor is working fine. Then I did the same thing again but the battery trick won't fix it :(

Will an external monitor help? Can I get in there and brighten it somehow? Do a system restore? I've tried all the keyboard combinations I can think of :(