voltage cutoff problem mmm v3

[riverat1540]

just got mamba monster v3 and seems to be something wrong with voltage cutoff ive tried it with both my 3s and 5s bat and it doesnt arm when set at 16.5 or 9 with either battery but if i disable cutoff it works fine and arms no prob. i know for a fact my batts are fully charged, will i have to send this in?