Thinkpad X1 Carbon 20KH006JIX - Bios recovery file name?

[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. What name should I give to the file and if you can tell me also the right file, I think it is BootX64.efi. or if you have other suggestions. Thanks in advance

[palace]

I found that the file I need is .fl1, can the procedure still be carried out? should I rename it?