AC460 controller serious failure..

I posted a question last week related
to a bus error on an AC460.
It was limited to backup CPU..

This afternoon I rebooted these cpu modules ..

I did the same for all the backup cpu whilst
the primary where "Active"..

Everything has been ok until I tried to reboot
the last backup cpu..
After initialisation (Loading L phase) this cpu
caused a complete bus error of the entire node.
All the cpu,carrier board etc.. went in fault .
The node has been unable to boot until
I withdraw the last board to be booted that cause the failure and a complete power off/on of the node.
After this the node has been able to restart.

I will check the Cpu module on a spare node to see if the problem persists on a different cardfile
But I still doubt if it could be a RF522 cardfile problem
or a fault in the cpu board itself.
Fortunately this node was not so critical even though
was connected to many TRIO remote I/O with many Digital loops with initial command set to a neutral state,
that did not affect the Power Plant where the system has been deployed
I would like to know your opinion.
Thanks a lot
Paul