Last time I rolled one of my units I just took a long hollow fence post, placed it over the grip area (with a rage to protect the grip) and lifted it right back in place. Worked like a charm!

Glad no one was hurt!

 

I am not sure why the grip would turn. I think you have the same as my grips made by moose. the directions noted if you couldn't slide them on all the way to apply heat and remove the grip from the bar and then reapply wd-30 a few times and retry. my thought if you used glue they will be on for good, me I can't stand my bars bent slightly so trying to rebend them will never be satisfactory. I would spend the money and buy the new bars, remove the heated grips and install them according to the directions, hopefully the grip will be tight, if not glue would be your only option. good luck and I know the feeling when the borrowed quad ends up smashed.