This is the second Motor Carrier board I’ve had, and the second to fail!
I’m just really lucky I caught this in time as it was a proper fire inside a droid I’m building.
The first board that blew up went short circuit, and I couldn’t figure out why, I was running from a 12V bench PSU, and when it happened the PSU was clamped at 2 amps, so it caught the issue and switched back the supply. So no noticeable damage on the MKR shield but it was now short circuit on the Vin rail.
This time I had my full system sat on the bench in front of me, I had been running it for about a week.
The MKR Motor Shield is powered by a 12V, 10amp Dc-Dc converter powered by a 12V NiMh battery fused at 8Amps. The system was switched on but in standby mode, e.g. my code was running all the motors were switched off (zero duty ) so basically nothing was happening. I was just tweaking some code and the board burst into flames!
Looks like the mosfet power switch section!
Seeing as this is the second time this has happened, I’m sure this is a defect in the design. I contacted Arduino tech support the first time it happened but have had no solution or replacement.