Same happened to me. Everything is still working.
Here is a picture:
Edit: Something weird was with the picture. :gp2x
The Blue circles are missing. I'm missing 2 of those. I think
Ehhhh the picture is 2272px × 1704px <_<
You can try to just put Firmware 2.0 back.
http://www.gp2x.de/cgi-bin/cfiles.cgi?0,0,0,0,42,1472
When on the first GP2x screen hold start and select. :D
btw. Put new batteries in your gp2x