Possible CPU Board failure - need to review

Hello guys,

So there is an HP Integrity RX6600 server, which simply cannot be turned on. When user power-on the chassis, the server goes into Power-off mode immediately (afer 5 seconds)

After reviewing logs (MP logs), we found that the chassis hasn’t any chance to do basic checks and stop at beginning so it has to be a critical section of the server like (CPU Board or CPU modules)

Log Entry 64: 09 Aug 2017 19:19:48
Alert Level 7: Fatal
Keyword: BOOT_NOT_DETECTED
No events were received from system firmware
Logged by: Baseboard Management Controller;
Sensor: Processor 
Data1: FRB2/Hang in POST failure
0x20598B6054020430 FFFF036F00070300

Log Entry 107: 09 Aug 2017 20:34:16
Alert Level 7: Fatal
Keyword: MISSING_FRU_DEVICE
Missing FRU device - Processor 0
Logged by: Baseboard Management Controller;
Sensor: Entity Presence - Missing Device
0x20598B71C8020700 FF20807115250300


[mp0014c29c5978] MP:CM> SS

System Processor Status:

   Monarch Processor: 1

   Processor Module 0: Installed and NOT CONFIGURED 
   Processor Module 1: Installed and Configured

So basically we've ordered second handed items like:  Power supply module, CPU board + CPU modules for replacement on the server.

Power Supply modules are OK, we confirm that. However we’re not sure about CPU Board. Because as soon as we replace the old CPU Board with new CPU Board that we purchased there will be no AC power indicator on Power supply not or the Power button !!

When we replace it back with faulty CPU Board, AC power will back on both Power supply and Power button.

 We even tried to only replace 1 CPU module (new one) on the old CPU Board (Processor Module 0: Installed and NOT CONFIGURED), but again same problem (the server power-on and after 5 seconds it will be turned off).

Could you please guide us about this problem. is there anything else i can do for troubleshooting ? have you faced this problem before ?

Thanks.