As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN ESSENTIAL BUSS POWER IS LOST, THE ELECTRONIC STANDBY INSTRUMENT (ESIS) REBOOTS AS IT SWITCHES TO BACKUP BATTERY POWER. THIS RESULTS IN A 3 MINUTE AND 20 SECOND DELAY WITH NO STANDBY INSTRUMENTATION. THERE IS A RELAY IN THE CIRCUIT THAT SWITCHES BETWEEN ESSENTIAL BUSS AND BACKUP BATTERY POWER. IN NORMAL OPERATION THERE IS A 'BLIP' IN THE DISPLAY AS IT SWITCHES POWER. THIS UNIT COMPLETELY REBOOTED AS IT TRANSFERRED.