Freezer door was left open overnight-freezing problems ever since

Our GE side by side freezer door was left open overnight. Ever since then the freezer hasn't acted right. At first it was barely freezing on the coldest setting. I turned it off and defrosted for a few hours. Tried again. No difference. It wouldn't even make ice. It limped along like that for months before someone suggested I cut the power to it for a few minutes to reset the motherboard. That helped dramatically....but you can still only turn it up to 6...anything past that and it seems to go into some kind of defrost mode and starts defrosting the whole freezer. If left overnight or longer it will completely defrost everything and get warmer than the fridge. The fridge side is working fine though. Any suggestions? This expensive fridge is about 8 years old....I think if a top of the line 8 year old fridge like this can't handle a door left cracked open overnight, then its a huge POS. Personally I'll never buy another GE product in my life. My parents and aunts/uncles have fridges as old as me that work great. It seems like modern fridges are cheap, low quality junk......figures. So much for things improving with advanced technology :(