Otis 311 drive fault

I got a 311 shutdown on a F53 converter AC UVT I tried to clear the fault from the DBSS but seems to come right back any Ideas on what might cause this fault? Car won’t run on inspection either it does pick a direction but the brake doesn’t pick and the drive doesn’t energize. I have 480vac across R,S,T. C relay is up? Thanks for Any Input.

If your 3 phase to the drive is good but the drive thinks it’s under volt, the drive has to go out. Not sure if others dive deeper into those drives but we just send them out.

Do you send them out to unitec? Drive screen just keeps flashing 421 tried clearing with a blue tool still no luck! Also got the drive to show an f47 but the motor thermistor meters closed don’t have my 30vdc on it?