OVF 1 OTIS DRIVE

Hi All,
I need your help regarding OTIS MCS 321 with OVF1 controller ACA21290BM1, 18 ATF motor. The Symptom was the Lift suddenly stopped and trapped the passengers, we tried to run INSPECTION UP or DOWN but not possible. SVT tool showed IGBT desaturation, we replaced one IGBT that defective and fixed the drive again but the same an issue, IGBT desaturation still there
What could be the problem? why the lift don't move at all in INS mode?

You should change all the IGBT's at one time and check the Cap's for leakage

thank you so much, we rectified the issue. the problem was lOgic board inside the OVF30 especially in the IGBT gate module, we replaced the gate module from the obsolete board.