HP ML370 G6 no response to power button

[major_majonez]

Hello, colleagues. There is an old hp server that is used as a network storage. About a month ago I noticed that he was in standby mode (the yellow indicator of the on button), although the bios mode is always on, I tried to turn it on from the button and through the ilo, but there was no reaction. After long checks of the power supply and the power backplane board, it turned out that they are serviceable (maybe). Then I started removing all pci devices, left 2 processors and 2 RAM sticks, everything is the same (there are standby voltages and 3 V on the power button), green indicators on the motherboard behaved the same as in stanby mode, but there was no reaction to the on command. It turned out that after removing the cmos battery, after powering the power supply, the motherboard immediately automatically starts and works as if nothing had happened, but after a few days the same symptoms.

A couple of weeks later, even after resetting, the cmos did not always start, sometimes there was a black screen, sometimes a red diode on helth led, could be in standby again after the first reboot.
What I tried: changed the bios to backup, reset nvram, changed the power supply, checked the cmos battery (3.01v), checked the voltage drop on the data+/- lines, the power button wires, there is no result, it just seems that every time the motherboard is harder to start. (Bios and ilo version is the latest). I searched the forums and found only one similar case with a solution, the solution was: replacing the motherboard.
Perhaps someone has encountered this, because my hands have already dropped. I don't even know about what the problem is. 

[support_s]

System recommended content:

1. Advisory: HP Integrated Lights-Out 2 (iLO 2) - iLO 2 May Stop Responding After Pressing the Physical Power Button on an HP ProLiant DL / ML G6 Series Server

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[Tam92]

Hello,

This looks like a hardware issue to me and i am glad you have tried almost all the possible troubleshooting steps.

I would request you to log a case with the HPE support as it would require the system board replacement.

Thanks,

TAM