Pioneer HU installed and working completely fine, all of a sudden craps out, any help?

Sounds like a classic issue of a short in the speaker wiring.  Remove the head unit and inspect every connection - they will likely need to be re-done.  If you still have an issue after that, then you look at the speaker connections themselves and insulate/inspect for shorts.  if any bare copper wire is visible anywhere, it needs to be taped up (3M electrical tape, i use Super 33+).