Show some photos of the all the wiring.
How the supply wiring is done is very important, as high currents in the wires can induce spikes above 5 volts.
If any the logic circuits see above 6.5v for micro seconds they can be fried.
It is easy to get the smoke out, but hard to get it back in again.
In particular photos of all the power wiring to the drivers and the power supply.