I'm working on a project involving several stepper motors and two shields. However, during the course of the project my arduino stopped being recognized by the computer. At this point, it isn't even showing up as an "unknown device" in the device manager. I've been able to run the bootloader using the gammon tutorial (using another, working arduino to program the broken one) but it definitely seems like I managed to fry the ATMega16U2. (Results of board detection from the gammon github code tell me that programming mode is off.) I'm unable to use Flip to reprogram it because I can't even find the device (have reset to DFU mode.)
I've gone through two (genuine) boards now, both a mega and an uno, with the same issue. Is this something that I'm doing incorrectly? I upped the I2C rate in the code to try to move my motors faster, but I really don't know what else would have caused the ATMega16U2 to stop working. Thoughts?