I’ve returned back to an old job but I had left on good terms, and in fact my old boss ended up wanting to keep me around as a freelancer… eventually when my newer job wound down and I needed something more permanent it just kind of made sense to go back to the old job where the boss there still wanted me around anyway.

So when it is on good terms it’s easy. In your case it doesn’t sound like you left on great terms, and it is quite possible your former boss is going to give a bad recommendation on having the company allow you to come back. Personally I might consider that a burned bridge at this point, but hey anything can happen so all you can do is give it a go. My suggestion is to talk to your former boss and just accept blame for whatever they want to throw at you, and hope they at least give a neutral recommendation on you coming back to the company. In the end you’ll have a different boss anyway so coming in it’s a new start for you.