It sparks when it’s just the vescs as well.
Some things I would check -
Battery - Is the total battery voltage measured at the main power plug within normal range? Also check each series voltage on the BMS plug to see if they are roughly the same.
Vesc - Check the resistance between the positive and negative battery terminals on the VESC. Is it shorted? Check the DRV chip (the big long microchip closest to the motor connection). Does it have a small hole anywhere in it?
You can power up the VESC with your charger and plug it into a PC by USB to see if it’s still working while by-passing the battery altogether. Then if it connects and powers up, with no DRV error your vesc is probably fine.
Anti-spark key - these things have a resistor or something in them to prevent them from sparking. They can fail and not work right or at all. Maybe try with a regular XT90 key. A spark is OK AFAIK, just bad for the contacts over time.
Opinion Those VESCs are cheap Chinese versions. Built with lower quality components usually and are suspect.
Your spark key got unplugged half way, causing all the current to go through the resistor (also causing the black marks). Since the resister got eaten up it sparks.
Thanks for the help! I’ll try it once I get back from work if I can muster the energy. It wasn’t a normal spark, it was way too big for that. I actually have some nice blisters on my fingers now from the burn.
That was the second one I tried to solder on. The one I managed to pull out because I was expecting the spark. The first one is completely fused together. Can’t pull it apart, that’s y I cut it off instead. no gaps as far as I can see though.