Have you tried reinserting the module? Also try inserting this PM into another slot in the UPS. If you try both of these and you still are having issues you should call into your local APC support line for further troubleshooting.
I recently added a power module (SYPM10K16H) to my Symmetra PX, the status says on & ok but Serial Number, Firmware Revision and Manufacture Date are not available.
The two other modules work fine.
I got the same problem on my symmetra px
Need help please.
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