I did the same thing thing with my m080,but i messed up trying to unroot and had to go back to a backed up version on my card. So it was'nt a clean reinstall on all the backed up apps I froze. Long story short my files are'nt exactly stock any more and I was wanting a clean stock m080(like I should have had ;-) )
To do your backup just boot into the recovery screen at startup and scoll to the backup option. It will save your rom ,then go to that file and rename it from what the GNM recovery named to keep it safe.