When that’s sent, it tells the firmware to write the matrix to eeprom. Something happens and it chokes on it and the arduino resets… but seemingly after the eeprom is saved. I don’t readily see anything unique about what is being done in the firmware, other than a much larger amount of data is saved.
We can test things out by having the eeprom save differently. Right now, the routine saves the entire structure, but we may be able to change it to save the actual values, one at a time, to the eeprom. It will be slower, but maybe more reliable.
What caused ground control to crash? Was there an error? Was this during the calibration?