Here's what I think I saw...
A rock and roll band shows up in a town to do a show. Probably. Like I said, I never really saw it. Just typical rock n rollers, except it's one of those 80's permutations where when they start to rock it sounds like a Michael Bolton song. I'm just saying I don't think the rocking corresponds with the level of rocking promised.
Here's the rub. Hitler lives in this town, and he's in no mood to rock n roll. So he has the members of the band whacked one by one, one literally with a weed whacker if memory serves.
But you can't kill rock and roll a second time, so the Hard Rock Zombies return to do a power ballad, I think, with a girls' name in like Debbie or Cammie or some shit and if you're not in a room with 150 drunk people laughing their asses off it might not be as funny but if you can arrange for the 150 drunk people by all means I recommend it. There's more.
Homicidal NAZI dwarf. Don't remember if it's the Seinfeld guy. Or Peter Dinklage.
Eva Braun is in it. She's a werewolf.
Everybody dies at least once in this movie, but that doesn't stop the entire cast from coming back for a final showdown in a cellar somewhere with green and violet backlighting and nobody is really in it for the politics or offended that Hitler is, well, Hitler, it's all about the power of rocking. Probably.