A certain power rail on RCB is unused, however enabled and monitored. In some cases, this power rail falls down below the under-voltage threshold, then the power control logic immediately shuts down the RCB, and RCB can come up after the power rail recovers.
 
    When this condition happens, RCB in a system resets with the following message in Junos syslog:
 
eventd[4680]: SYSTEM_ABNORMAL_SHUTDOWN: System abnormally shut down

   Given an individual characteristic difference on an unused power rail, it's possible that RCB operates normally without experiencing this reset issue.​
 

    Juniper Networks has developed a field solution through a new FPGA firmware that properly disables the unused power rail.

    ​Please contact JTAC so that the RCB FPGA firmware can be upgraded.

04/07/2020 - Remote power cycle procedure has been added.
05/01/2020 - Step 5 was missed...replaced with step 6.