HP EliteDesk 800 G6 Desktop Mini PC - boot issue

[rtstorm]

Hello, i got this mini PC that won't boot when the button is pressed. I try to clear CMOS remove the battery etc. I managed to power it up if i hold the pwr button, connected the power supply, and continued holding the power button for 4-5 sec. Than PC boots normally and work fine. If I want to turn it off the Windows show 'Logging off' than screen get blank and PC wont turn of, if i hold again power button i can do a hard turn-off. After that, if i press the power button the PC show LED and that the fans slowly start to spin from low to high rpm and stay at full. On one occasion when i managed to get into the windows i updated the BIOS and the process finished fine but that did not help.
My opinion is that this cloud be a bad BIOS or something like that, does anyone have a similar issue?

This is the model link

[rtstorm]

Oh now i see that i posted this is the wrong section. admin please move the thread to correct section for Desktop Pc

[SMDFlea]

Moved topic.

[rtstorm]

Update:
I disassembled the PC and inspected MB under the microscope, i found that 2 diodes were broken and i found short around U10 IC (WGI219LM) this is LAN IC. I try to inject 1V and see that this IC is getting hot. I removed it and the short is gone, now the PC is working fine except the LAN is not working. There was probably an electrical shock coming into the PC from LAN (maybe a thunderstorm).
Can you guys recognize the 2 diodes (SOD-923 size i think) that have the marking "X-1"?
Also, I have checked the "KFG" component and there is no short even it looked burned.

[rtstorm]

Here is a better picture of that X1 diode (it is 1mm x 0.5 mm), i am not sure if the 5V Zenner diode will do the work, or if there should be a diode with higher voltage.

[rtstorm]

My name is Takudzwa Mutambu . An aspiring repair technician from Zimbwabwe

Hello, do you have any info of the component that i am trying to identify?