As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 8678 ENROUTE PDX-MFR AIR TURNBACK/DISCREPANCY: GDU 620 FAILED IN FLIGHT. AIRCRAFT WAS RETURNED TO PDX. NO EMERGENCY DECLARED. LANDED WITHOUT FURTHER INCIDENT. CORRECTIVE ACTION: MAINTENANCE REPLACED THE GDU 620 DISPLAY AND CONFIGURED. GROUND OPS CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.