Damaged/shorted Pixhawk 4?

I was modifying the firmware and at one point the Pixhawk 4 started turning it self on and off in about 3 seconds interval. I thought it was a software issue at first, but then I noticed the Pixhawk 4 is abnormally warm. I was able to get it connected to QGC and see the normal information before it starts shutting down over a lower powered USB source (unpowered hub), but on a higher powered USB port (chassis port) it gets noticeably warm very quickly and emits a burning smell. I can only conclude that there is a short somewhere inside the board. When testing after the issue happened, there was no cables connected other than USB and there is no visible damaged component on the PCB. Reflashing the firmware did not resolve the issue.

When the issue first appeared, I modified one of the examples to control “actuator_control”. Can firmware cause the issue? There was also a 5V power supply on the PWM_IO_OUT powering a servo, and I was occasionally shorting the 5V to ADC 6.6V.

Any idea what might have caused the