When I connect my focbox 1.6 to Vesc tool 6, i firstly went to update the firmware from 5.02 to 6.00 and then I went to setup an old hub motor (picture 1) which originally had a 5 pin hall sensor cable (picture 2) which I converted to a 6 pin cable (picture 3). I plugged it into the Vesc and When I got to the page where you have to select the motor poles I paused the procedure for approximately 5 min to look up the number of poles, but when I put the correct number in and went to start detection I noticed that the Vesc disconnected itself. When I check the Vesc I noticed that was no longer any light anywhere on the controller, so opened it up and I noticed that as soon as I would connect it to power, the diode (picture 4) gets extremely hot within seconds. I also compared it to the other working focbox I have and noticed that on the broken one the left side of the diode is shorted to ground (picture 5), but not on the working one.
Test resistance between 3.3v and ground on the swd port. If it’s less than ~2 ohms probably the stm32, but the canbus chips on these can also short the 3.3v rail. If it tests fine (high kohms) then processor is probably good.
Can also check phase to phase resistance to see if they are all about 60-80?kohms. Looking for consistency to see if any mosfets are shorted.
Note that you’ll need an stlink v2 to manually load the firmware if you do have to replace the stm32. It won’t load via USB the first time.