[FPV] First run of a new stack without capacitor. ESC goes BOOOM!
Well, they say "use a capacitor when you fly with 6S batteries".
Here you can see what can happen if you have a powerful ESC and quite agressive motors.
My guess: The caps could not take any more energy from regenerative braking and the voltage went beyond their specs.
One of them finally failed and got a short circiuit, heating up instantly and spreading liquified PCB-copper traces everywhere.
No worries - it was repaired just a few minutes later:
It was just a few caps that blew up.