overvoltage error on SureStore E Disk System SC10

[GraceO]

We have a SureStore E Disk System SC10 connected to an HP 9000 rp5470 running HP-UX 11.11. stm is reporting an overvoltage error on Controller A. This happened a couple of months ago and reseating the controller seemed to have corrected the problem. All lights on the back of SC10 do not indicate any problems...no lights are amber. The power supply was even swapped out, but the error remains.

Has anyone experienced this before? Should I replace the controller or could the backplane be faulty? Can I swap Controller A and B around and see if the errors come from Controller B to isolate a controller problem?

Any help would greatly appreciated!