I would use something like Blue painters tape or frog tape, not something like Gorilla. Gorilla is TOO sticky and might leave residue or even cause more damage (stick too much and pull it too far out), which frog tape will not. When you say it didn't do it, what happened? Did it not stick or did it not pull the dent out? Tape would usually be the recommendation, but disassembly might the only option if that didn't work.