Thinkpad X1 Carbon 20KH006JIX - Bios recovery

[palace]

I have a thinkpad x1 carbon 20KH006JIX, after a bios downgrade to 1.08, what happens is that neither usb nor ssd peripherals are read. Accessing the bios works and so does diagnosis. Since the usb does not work I cannot update the bios in the classic way. I would like to force the upgrade. Does anyone have any advice or guidance? the file to be flashed should be .fl1, I don't know whether I should rename it or insert other files