Forgot to unlock critical and cannot use OST now

I purchased an unlock key for Nokia 7 Plus. I unlocked my bootloader a couple months ago when you sent me the unlock key, but I overlooked the unlock critical part, and I've since updated my N7P to the october update, your workaround doesn't seem to work and I get a "Failed (remote: failed to verify)" when trying to run the fastboot flash unlock command.

I want to flash my phone to the full stock ROM using OST. But as you'd know, I am failing to use OST as flashing for critical partitions is not allowed. It remains stuck on flashing abl_a.

Is there another workaround I can try?

Thanks in advance.

singhnsk

The unlock is no longer possible after the August update without downgrading. There's a workaround though:

Since your device is already unlocked, you can root it and then write the old abl and xbl from the stock B2N firmware.

Once you downgrade the abl and xbl, then you can go back to download mode and unlock critical using the same unlock key.

After that you can flash the device using OST LA to revert to full stock ROM.