msa 60 amber fault light on but no error anywhere

[dzila]

We have a DL 360G6 with P800 connected to a stack of 2 MSA60 with SATA disks. It has been working fine for 6 months. About 1 week ago the front and reat fault LED went on. No errors logged in system logs, ILO logs, or SMH. No errors reported from the computer. No operation took place for at least 1 month. I attach the diagnostic logs.

I would be grateful if someone can have a look and offer possible ideas. We cannot bring down this array and start experimenting by removing and replugging modules without causing significant problems to our users.