Wow! Many thanks!
So I find out how to do this. You have to make flash drive with free dos. Than to download latest bios for your model. Put RCV pin in recovery mode, insert prepared usb flash and listen for beeps. It is going to take 2 minutes. At the end there is going to be two long beeps...
I bought one a couple of days ago. I wanted to make a router. My idea is to put LTE card, wifi card to have wifi5 and intel card with 4 ports via riser. But I am unsure how I can use LTE mini PCI-E and wifi card? Where do I connect another card?