Question Pc Restarts all the time after 2 seconds of fan. With onboard Graphiccard it works. With extern it does not. Need to reset or find settings

Oct 27, 2020
My laptop hp zbook g3 (15) restarts all the time. It boots for 2 sec and then restarts. When I take out the extern m2000m graphic card the laptop works fine. When I put it back it happens again. It all started when i put in an usb stick to install Linux mint.
The same happend to me before when I was installing Ubuntu!
The solution then was to take out the grapphic card and the next day i could still change in the bios the graphic card. Now it this option is not shown anymore.
Yesterday i already called for 75 mins with some hp support who wanted to call back but never did!
Since this probelm happend before and was solved i believe that the graphic card is still working.
I already tried all resets. Also with cmos reset it did not work(took out battery over night) once with extern graphic once wirhout. But the confussing part is, that the version of the bios stays the same.
The last idea i will try todsd is to reinstall the windows from now bios to uefi. Do you have any other ideas?
Thanks Dominik