Really sorry for your loss, having been through something similar with our family and our previous dog you have our most sincere condolences. :<

Absolutely not, no. Bad behaviors are often self-reinforcing and you basically have to start at the beginning to find the behavior you want them to do and then reward them by doing that over the existing behavior which you don't like which essentially overrides it.

dogs are basically perpetual toddlers and a normal child will eventually grow up in some way to compensate. a dog will never learn if their owner will never teach them. bark baby forever!