What was found
GROUND EVENT, APU FAULT MESSAGE 49-41250 (STARTER CONVERTER UNIT). START SYSTEM INOP. MAINTENANCE REMOVED AND REPLACED THE STARTER CONVERTER UNIT AND COMPLETED ALL OPERATIONAL CHECKS. AIRCRAFT RETURNED TO SERVICE. GROUND EVENT- APU FAIL TO START. MAINTENANCE REMOVED THE STARTER CONVERTER UNIT TO CHECK THE CONNECTERS THEN REINSTALLED THE SAME UNIT AND COMPLETED ALL OPERATIONAL CHECKS. AIRCRAFT RETURNED TO SERVICE. GROUND EVENT, APU FAIL TO START. MAINTENANCE PERFORMED FIM PROCEDURE 49-40-00-810-803. REMOVED, INSPECTED AND REINSTALLED BOTH THE STARTER CONVERTER UNIT AND THE STARTER POWER UNIT. TEST STARTED THE APU TWICE AND ALL OPERATIONS NORMAL. AIRCRAFT RETURNED TO SERVICE. TROUBLESHOOTING THE APU,