no tail lights

My daughter has a 98 lumina in Va.,I am in NY. No dash lights or tail lights, she took it to a shop today and he said he checked all the fuse blocks and did all the diagnostics he could and found nothing. They want to start taking out the seats and carpet to continue looking for a cause. Sounds drastic to me?
Any ideas where the issue could be?

brake switch. Test for 12v at the brake lights. If no 12v and the fuse is good, the switch should be bad.

If those are all good, check the fuse for 12v. One fuse can blow that allows voltage to go to another fuse. Is there anything else in the car that doesnt work?

if the high-mount brake light works, but none of the main lights do, she needs a multifunction switch. It's a very common issue, and all power to the rear lights (except the high mount stoplight) and the dash lights is routed through the multifunction switch. It will require removing the air-bag and steering wheel to replace. There are two different ones depending on if her car has the accessory controls on the steering wheel.

AC-Delco D6226A (w/o accessory controls)
AC-Delco D6214A (with accessory controls)

She took it to a shop and he found seveal spots with "green death" some between the front and rear of the car and some in the rear light area, also some up front near one head light. I know where this car has been for about five years but the last owner purchased it from a used car dealer,I wonder if it has been in a flood.