Drobo

Drobo won't Restart

The Drobo 5N when restarted goes through not check of drives but doesn’t exit.
All drive lights appear yellow and fans or drives are spinning. yellow light on the front left bottom.
Drobo Dash doesn’t recognise the drive.

The system was shut down before I went away for a holiday. When I returned and started it up, it didn’t start.

Any Ideas?