Bootloop on ProBook 450 G7 nothing helps

[CarMagician]

Hello,

I have a big problem with my Probook. 

I did a install of a second windows 10 on a different partition.

This went all good so far. I shut my laptop down. I could use both windows versions.

We fast forward to the next day.

I start my Probook and it does not recognize my fingerprint. Never had that before. 

Okay entered my password. -> instant reboot. 

Okay I thought look at the start entries in bios. 

Power On, Press F10 for startup menu. I get the message of entering the setup. 

I have to put my password in, after that HP Logo with message in the corner about entering setup. 

Instead of setup I get a reboot. Every time. Can't even get anything done with a live usb stick. 

Tried every possibility, Pressing ESC, F1, F2, F8, F9, F10.

Every time I have to scan my finger which does not work, so I enter my password. -> HP logo -> reboot. 

Tried a hard reset by unscrewing the back cover and unplug the battery. 

Unplugged the CMOS Battery -> getting POST message and reboot after that. 

Tests so far: 

Installed only 1 tested working RAM in both of the slots -> no change

Installed only M2 -> no change

Installed only HDD - > no change

No drives at all -> no change

Testes M2 with windows installed -> no change

Power via battery -> no cange

Power via battery + charger -> no change

Power via charger -> no change

Trying Windows Key + V -> nothing

Trying Windows Key + B -> nothing

Maybe one of the bios chips is gone? CPU gone?

ANY ideas?

Regards

CarMagician

[SureStart]

I got a bootloop because of buggy Sure start on a very recent machine, indicating that they still didn't fix it. This thing is causing so many restarts. Even a normal power on takes 2 mandatory resets. And of course confirmation codes 24/7.

The mentioned procedures didn't work. Removing hardware did nothing. Clearing CMOS did nothing except resetting clock. Nothing else  works on nowadays BIOSes. Emegency procedures with USB etc were cancelled long time ago. Web guides are usually invalid.

But here's one shortcut that is not well known: press all arrow keys. That helped me to reset the BIOS and enter it. So glad i didn't need to go through RMA thanks to this thread. Maybe it will help you.