Lights behind dash not working

Check the fusebox for the component fuses to which the lites are controlled by.

Especially the tail light fuse. Many cars when the tail lights fuse blows, the dash lights go with, same fuse/circuit. so you won't be driving around without taillights and not even know it. This is especially true since you mention loading and moving things in the trunk, may be no coincidence

Repair the wires in the trunk before you blow any more fuses.

I had the same problem and found the insulation on two of the wires near the trunk hinge on the passenger side had worn through. The wires were next to each other and would short out intermittently.

Were is the fuse for dash lite

This is the #1 fix. is not hard at all but it is time consuming. so set aside about 3 hours of your day for this. https://www.youtube.com/watch?v=ebTS25sNOHQ

Our Buick Century Custom 2000 had the dash lights go out completely except for the gear shift light. Took it to a mechanic shop and it was a fuse. I recommend this as a first shot at fixing dash lights out.