if your ets/abs light comes on it's most likely your brake pedal switch...it's an enexpensive fix....it's pretty common on the ml....
as far as the hatch, i had the same thing happen to me....turns out for some reason they put a plastic piece on the hatch lock assembly that cracks! i have to lock/unlock my hatch from the inside.....the dealer quoted me a little over $400 for the lock assembly