During Nexus 7010 upgrade from 5.2.1 to 5.2.3 code, the X-bar module in slot 4 keeps powering off. The %MODULE-2-XBAR_DIAG_FAIL: Xbar 4 reported failure due to Module asic(s) reported sync loss (DevErr is LinkNum). Trying to Resync in device 88 (device error 0x0) error message is received.

This error message corresponds to diagnostic failures on module 2. It could be a bad connection to the X-bar from the linecard, which is results in the linecard being unable to sync. Typically with these errors, the first step is to reseat the module. If that does not resolve the problem, reseat the fabric as well as the module individually.