2006 Pontiac Grand Prix The trunk will no longer open

If you have the folding split rear seats, the seat back folds down to access the trunk. If not, I'd probably remove the rear seat. Your owners manual may have some info on folding down the seatback.

Another thought, if you could access the voltage wire at the rear for the trunk latch, hoping the short is toward the front somewhere, then you could use a jumper for voltage. Don't know how wiring circuit is routed, it could be under the carpet, under door trim, under the vehicle, almost anywhere. If you can find the wire harness at the rear, I can give you the wire color.

Why didn't the shop fix it?