Well i was trying to keep the thread on topic but no... it very likely isnt the vamo. Most.often when I hear this kind of issue with a vamo it is centered around the use of batteries that are not high drain batteries, which the vamo requires. It could be a poor power output issue, a bad board, coils, or could even be related to the juice makeup he uses.
Frankly it could be any number of things. Could it be a bad vamo? sure, but just jumping to that conclusion without troubleshooting it first is kinda pointless. Besides, what if it is an easily correctable issue and he gets a new vamo and the same thing happens? Its worth giving more info and checking it out first.