Uninstall CFW is almost never a solution and pretty much always a bad idea. But… if one is dead set on doing so, then do it according to The Guide, and not with some YouTube video.
This is the most safe method of removing all homebrew and CFW stuff and nothing bad should happen when following it (including Data Management crashes). It still is of no use to remove CFW.
So. Looking at the troubleshooting page gives:
Any reason for using the BannerBomb3 method? I guess you have run the Seedminer part, got your movable.sed and can now proceed with