I run my windows 10 Home on an Asus laptop and do not want to upgrade to 11 until they have fixed all the bugs their patches produce, so I have been using an old Amilo Li 3710, updated to 10 Home and with an ssd to run various OS from a bootable usb. I was changing the Bios from Legacy to UEFI when it switched off and left me with a black screen. I can get in the Bios and Boot menus but no further. I dismantled the machine to unplug the CMOS but could not find an original or a lithium "coin" which might have been installed in the update. Does anyone have any ideas on how to get back to Windows, or is it permanently fried?