It is possible ( I think ) but I cannot give specific instructions for that and what it would require is a roll back to 1.3.2 first, then progress from there. If you go over to the Phantom Pilots forum and do a search you will find many threads on downgrading. It is a bit tedious, but at this point you may have no other option to remedy the mismatch. I know hindsight is 20-20 but the update to 1.11.2 should have not been performed assuming the existing firmware was much older. Go here and do a few searches: