Ok I wish I wouldnt get banned from my power going off n back on it thinks I left but I didnt :( any help anyone?
There's no foolproof way of telling intentional and unintentional disconnects apart, unfortunately.
First-time bans are generally quite short in duration. If it's happening enough to be a serious issue, I'd consider looking into what is causing the power outages because intentional or not, leaving a game will hamper the experience for everyone.
The MCC Ban thread has more information on how the system works and, should you need to make an appeal, that's where to do it.
You can post in the appropriate ban thread linked below, but essentially leaving a match is leaving a match. The system knows you did it, but not why. And in order to not provide a massive exploit it has to treat every DNF as an intentional quit otherwise people would just pull their ethernet cable, turn off their xbox etc to get around it.