I would just either pull your current firmware and resign it, then it can be flashed with spflash, or patch one of the older firmware like 1.0.8 to work with V2 and sign it.
Replace images in signed package and use original scatter.
Both guides available on the forum.
https://forums.jtechforums.org/t/guide-fix-new-batch-f21-pro-speaker-issue
https://forums.jtechforums.org/t/lock-bootloader-with-custom-firmware
Then upload for ppl to use 