BobbyW

It could be the ESC's safety mechanism where it cuts off if voltage is too low. Probably the first thing you tried but if you've checked everything else maybe it is just the batteries after all?

Edit: I also didn't know Gens Ace made 5500mAh batteries in 65c? I can't find them anywhere online. Did you get them from a reputable source? Otherwise maybe someone sold you some fakes?