What was found
UNKNOWN MALFUNCTION 1 MASTER CAUTION (RIGHT SIDE) WITH NO INDICATION ON CAD. AIRBUS RESET DONE WITH SOME RESULT UPON LEVELING OFF AT ALTITUDE. A TESTFLIGHT EVAL FOUND RIGHT HAND MASTER CAUTION LIGHT BEGAN FLASHING AFTER ABOUT 10 MIN GROUND RUN AT FLIGHT IDLE. MASTER CAUTION COULD NOT BE RESET. NO ACCOMPANYING CAUTION OR WARNING MESSAGE ON CAD. FLASHING RIGHT HAND MASTER CAUTION COULD BE RESET WHEN TWIST GRIPS WERE BROUGHT TO GROUND IDLE. REMOVED AND REPLACED WARNING UNIT ASSEMBLY IAW AMM 31-50-00, 4-1.