Bodywork question - hard plastic bumpers

[WestCoastSVX]

I know there's a few on here that know a thing or two on bodywork so I thought I'd throw this out there.

My buddy has a 2007 Jeep Wrangler with the hard black plastic bumpers.

Someone hit it in a parking lot (didn't leave a note) and now the rear bumper has a large dent right on the corner. It's like the plastic is just inverted there, but it is such a hard material there is no give to try to pop it back out.

He has heard rumors from various people (who supposedly have heard from bodyshops, etc) that with plastic bumpers all you have to do is heat it up with a heat gun, and the bumper will pop right back out due to its "memory".

Anyone have experience with this?