I, and many others have the same issue with M1-ATX as well, and there are many posts on this. In my case, if it does not boot like you have described, I hit the reset button several times (4 or 5 times in 2 seconds) and then it boots up fine. The problem seems to be intermittent and probably has to do with the M1 or M2 giving the boot signal to the mobo before it has had the chance to fully power the rails.
Since not everyone has this problem, chances are if you replace the unit it will fix the issue. If you do replace it please post the results with the new M2 here.