Device with B402 in locked state

Firmware
1

I have a device with a B402 SoM that seems to have gotten into a locked state that I have not been able to recover from.

The device was previously running firmware with Device OS 1.5.0. I tried integrating that code with some code that we have been running on a Tracker One to run on the this device with the B SoM. In doing so, I moved the Device OS all the way up to 5.8.0.

The code ran for a short period of time, but eventually crashed. Since then, I have not been able to recognize the device over the serial port. I have attempted using the mode and reset pins (which we have connected to test points on our PCB), as well as numerous power cycles. Does anyone have any tips or next steps that I can try to get further along in troubleshooting/debugging?

Some additional context - the device has a CAN chip (TCAN4550) on it. We've got a SPI-based driver for the chip. When the code was briefly running, I did some troubleshooting on the CAN, which was not working. It seemed that there were issues with the driver, I'm guessing as a result of my having jumped up so far in the Device OS. I didn't get to dig in for too long before the device locked up.

2

I would use Device Restore USB to see if you can see the device at all by USB. You probably will not if the buttons did not work before.

If you can't the next possibility is to use a SWD programmer to restore the device by SWD. This can be necessary if the bootloader or softdevice was overwritten or corrupted somehow.

If neither of those things work, the device is probably no longer recoverable, or has a hardware failure.