When I do *#0000#, my N900 doesnt even display that much info.

It shows:

V 20.2010.36-2.002
RX-51, Nokia N900
© Nokia

All text is in a yellow bar overlaying the dial pad.

Are you sure it is running Maemo? Can you post screenshots so that we can take a look?

Try turning off the phone, plug in the USB to the pc and N900 while holding the "U" key on the N900 and look for a tiny USB icon in the top right corner on the Nokia screen. If you see it, you will be able to flash your N900.