Most secure and probably the best way of restoring dent sheet metal is taking out and putting back in dent sheet from inside. This method is used for most complicated repairs if any other method for dent repairing isn’t possible or didn’t work, this is the best one. It takes the most amount of time for repairing because you will need to take apart the upholster. After correcting the sheet, it’s usually needed to paint it as well. While disassembling it’s highly likely that something will break. Usually it’s the plastic “anchor” that is constructed in one way. When they are being taken out they have to be broken.
All the bends I recommend to be fixed as soon as possible, because of the deformation won’t go back to normal after the repair.
After disassembling the upholster and needed elements to get to the dent part. Hitting is done from the other side of the sheet so that it gets into the place where it originally was, or close at least. You will need to use a rubber hammer, plastic or something similar, make sure it’s not a metal one. You should hit in the most dent point of the sheet metal.
Depending on the success of returned sheet, usually you will need 1-2 hits to get it back into the normal position. If not you will need to hit it a few more times. If you succeeded in getting the sheet metal in it’s original form then there is a good chance you won’t need to paint it. But, of course if we needed to emery then you will need to paint it.