I opened up the SKIPPA and there are no obvious issues with the CAPs and the power and SATA connections seem to be OK. No indication of burning. I suppose it could be a dead HDD. Will test it tomorrow and advise if that is the cause.
It is not a power supply issue, I connected the power supply to the SKIPPA it belongs to and it booted normally.
Update: Took the HDD out an looked at its content with UFS Explorer Standard Recovery and the files seemed to be OK. I will do a HDD check to confirm there are no physical problems.
Ian