BIOS malfunction with MSI board (Z270 Pc mate)

[jakobbunse]

I can't access my BIOS anymore, and I haven't found anybody yet with the same problem.
My PC is running just fine, perfomance is great and so are the temperatures, except the BIOS. It is by far not the first time that I use the BIOS on this system but for some reasaon all I get is a black screen with 3 green dots in the upper middle of my screen. Once I am in this screen I can't do anything except shut down the pc. I recently upgraded my GPU and PSU but the problem occurred the first time when I added 8GB more RAM to my System. I tried removing the additional RAM and starting the PC with all the "old" components with which I already accessed the BIOS, but I get the same black screen.
I access the BIOS by pressing Delete until I see the message Loading Setup... in the bottom left corner, then after a few seconds the blackscreen appears.

My Setup is:
i5-7600k @4.8GHz
Z270 Pc mate
16GB ddr4 corsair value select
H115i Pro rgb from corsair
ASUS Strix rtx 2070
beQuiet Straight power 11 750W
WIN 10 home pro version 1809 build 17763.288

I dont think the Windows version has to do anything with it since I had the problem with 1803 as well.
I hope the explanation of my problem is understandable, thank you in advance.

 

[jojesa]

Click the Windows start button, click on power, press and hold the Shift key and click the restart.
Also try disabling Fast Startup

If none of those allow you to access the BIOS then (with Fast Startup disabled) power off, unplug the power cord, disconnect all disk from the motherboard. Press the power button for 20 seconds, connect power cable and power on.
See if pressing the Del key allows you to enter the BIOS.

 

[jakobbunse]

Thank you for your answer jojesa,
I tried out your suggestions but there weren't any changes. But what I noticed is, when in this blackscreen the pc will shut down immediatley with a short press on the power button as if the PC were in BIOS. And another note, I haven't changed any settings in the BIOS except CPU voltage and core clock, and haven't done any updates. So from the working BIOS to the problem now nothing really changed, what I find odd.