HP ProOne 400 G2 Legacy boot option unlock

[hooddy]

I have HP ProOne 400 G2. And I need to unlock legacy boot option to boot from Lumix usb to install it. Maybe I am rong but I think that there's is UEFI only. I ask HP forum to help but they answer me they do not support Linux and I can not boot from it and I can not install it (why?) and even if I install it (what?)... I do not know which BIOS provider is it. If I insert legacy bootable Lunix usb its just skip it and boot from internal preinstalled Windows 10. Please advice me to install Linux on it.
BIOS located there https://support.hp.com/us-en/drivers/sel...ku=T4R03EA

[frankr2994]

what distro/ version of linux are you trying to install? You don't have to install in legacy. There are no problem running newer distro's in uefi.

[hooddy]

It seems that in 1st I need to update BIOS. Current one is 2.51, instralled one is 2.12. There is a lot of fixes including legacy mode.
What about distro I need to install Astra Linux on my working HP (yep I'm from Russia and I approve to use this distro on it)). I suppose I need to write dist in UEFI. Found Etcher for it. Can check it at next week.
looking through the info on Astra it seems that it can be installed in uefi. So yes I'd make sure you have a x64 iso and write it as an uefi install with rufus. I don't think there should be an issue.

[hooddy]

Well... nothing is works. I sucefuky udate BIOS to current one. Create usb flash drive with Etcher. It wont boot from it. Its just skipped it and don't see it in BIOS. For sure Ill try another one flash drive but it seems that reason is in something another.

[hooddy]

It seems that I can not disable secure boot. I need a mod for BIOS. In BIOS (ok, UEFI) settings I can not see any Secure Boot enty.

[hooddy]

Ok we boot well from USB. Rewrote it for a few times with different modes. Boot with Legasy written in rufus. Etcher didnt boot. Have issue with graphics etc but its not bios related. So thread is done.

May be this :

https://www.rodsbooks.com/refind/