2000 corolla dashboard light doesn't work? How to fix it?

was it jumped backwards or the battery installed backwards at first look for blown fuses including the large amp fuses

May not be any fuse and if it was other things would not work either. It is most likely the sitch that controls the running and dash board lights.

The parking and tail lights are usually on the same fuse as the dash lights so if the outside lights are working it sounds like the instrument dimmer control has failed. The electronic bits inside the control for these lights sometimes go faulty. A temporary fix is to remove the wiring plug that attaches to the back of the dimmer control and put a jumper wire across the terminals. If dash lights then work then replace dimmer control.

UNDER THE DASHBOARD

I would replace the dash gage assembly. The board probaly has an issue & it's just more cost effective to replace the whole thing.