[Help Request] Write protection issues flashing Lenovo TS440 modded BIOS

I’ve got a Lenovo TS440 that I’m trying to add NVMe support. I’ve followed the win-raid.com/t871f50-Guide-How-to-get-full-NVMe-support-for-all-Systems-with-an-AMI-UEFI-BIOS.html guide (flashed current Lenovo BIOS, dumped to rom, modified with MM Tool to insert NVMe support) but keeping running into BIOS locks when trying to flash the modded BIOS back.

When I try to test the backup that I created with FPT, I get Error message 18: Secure flash ROM verify fail. Trying to flash the modded BIOS based on that file gives me Error 280: Failed to disable write protection for the BIOS space.

Following win-raid.com/t3908f16-GUIDE-Grub-Fix-Intel-FPT-Error-or-BIOS-Lock-Asus-Other-Mod-BIOS-Flash.html guide to troubleshoot error 280, at step 3 the files I extracted have an unknown protocol.

Original Lenovo BIOS is attached.

Any help would be appreciated, I’d love to have this machine running off an NVMe boot drive!