How did I fry my VESC, and how can fix it?

So I just finished all the soldering required for a build I’m doing. I wired four 3S 5000mah batteries in series, for a total of 12S. I had tested my VESC with 6S before (two 3S batteries in series), and it worked great. But as soon as I plugged in my 12S battery, I heard a pop (which could have been just the spark), and the VESC led didn’t light up. I tried powering it with 6S like before but it still wouldn’t light up.

So I have come to the conclusion that I fried my VESC. But I’m not sure why. As far as I know, VESC supports up to 12S. I even tested the voltage with a multimeter before to make sure I didn’t screw anything up and that the battery connections were correct. Could it be because I failed to use an anti spark loop?

Additionally, does anyone know if it’s fixable? Could it be possible that a small component like a fuse is simply blown and I can replace it?

What I also noticed was that if I wait a minute or so and plug in the battery, I’ll hear a spark. But if I unplug and plug back in within ten seconds or so I won’t hear anything. Not sure what’s going on. Any help would be appreciated, thanks!

I got my VESC from Amazon, so I was thinking about returning it, but I’ve already soldered on 4mm bullet connectors for my motor, so I’m 90 percent sure they won’t accept it.

Might be cause by he absence of anti spark loop, idk know much about VESCs…Did you have connected motor when you connected VESC to the batteries?

YOu have MayTech VESC am I right?

ALso you have to send pics so other more experienced builders can tell if it can be repaired…

Amazon selling the VESC. That;'s new. Please post pics of both sides of the VESC in question.