So far 2 boards have died and I am uncertain how they failed, is there a chance they could be fixed through software?

[AZeli.1]

I was using a Nucleo F746zg to develop firmware and in the middle of testing after consistently functioning for over an hour, it stopped communicating with the st link and started showing an overcurrent error. After further testing, the voltage regulator now outputs only 1 volt when it should be 3.3v and I got a "The interface firmware FAILED to reset/halt the target MCU" when i was able to access the board.

After this I bought a Nucleo F401RE and had the same exact thing happen, the board worked for many hours and then suddenly in the middle of outputting to stlink, suddenly stopped outputting data and I got a overcurrent error and a "The interface firmware FAILED to reset/halt the target MCU" error.

I heard that a way to fix this was to use stm32programmer to do a full flash wipe on the chip but I was unable to do that for either board since every time I tried to connect to the board it crashes the software or makes it go unresponsive.

I hope I can get these boards to work soon.

[AZeli.1]

So I just tried externally powering the F746ZG and giving it more than 500ma and it now works again, it just requires a really large current when starting, likely due to the broken voltage regulator.

it now uses around 300-400ma consistently when powered with 5v externally, and I still am unable to connected it to stm32cubeprogrammer to wipe the flash on it, which is worrying, whenever I hit connect to debugger, the program goes unresponsive.

[Karl Yamashita]

You say the I2C device was powered by a seperate PS, but do you have a ground reference from the I2C device to the development board?

[AZeli.1]

yes, I made sure to connect the ground reference from the i2c dev board to the mcu dev board.

[Karl Yamashita]

I've had an test engineer testing a board that I have given him. He took it to his desk and could not program the MCU. So I took the board back and was able to program it with no issues. Then we used his power supply and it failed. Turns out his current output was turned way down, lol

[MM..1]

Check thermal state on board components, somethink will be hot... and ofcourse disconnect all external

[AZeli.1]

I have been seeing if anything has been getting hot, the mcu was getting warmer than I remember it getting before when i powered it externally but not sure if this all that bad.

[Tesla DeLorean]

You can create current conduction paths, and if excessive or prolonged will cause the silicon to act as a fuse. Could fail open, or closed, with the latter something is likely to get hot

Excessive currents on the regulators can cause them to overheat and fail, you'd expect multiple parts to get hot.

In situations where you think your code is configuring pins that might conflict with other circuitry or voltages on the board, you can pull BOOT0 to VDD (on the NUCLEO-144 boards you can jumper this as the pins are next to each other on the headers), so that user code doesn't run and you can erase the part.