As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER BATTERY MASTER SWITCH SELECTED "ON", ALL POWER TO COCKPIT INSTRUMENTS AND LIGHTING SHUTDOWN COMPLETELY. RESELECTION OF BATTERY MASTER' 'OFF' THEN "ON", ALL POWER RETURNED. CYCLING SWITCH SEVERAL TIMES CAUSED NO ADVERSE EFFECTS. ALL FUNCTIONS NORMAL FOR REMAINDER OF FLIGHTS. CONTINUITY TESTING OF BATTERY MASTER SWITCH REVEALED HIGHER THAN NORMAL RESISTANCE. NEW SWITCH INSTALLED.