Well there's a lesson in there, first, don't follow any guides but the ones here on xda. Many people creating those youtube guides are following some 'generic' instructions that work for some android devices but not others (and the authors don't know which devices they work for or don't work for).
And second, I'm guessing here but did you do a backup of the partitions you changed? Did you use qfil to make the changes you made?
and last, what variant of the G8 do you have? Sprint? At&t? If it's one of those that causes additional problems, because they don't make their kdz available. Without a backup of one of those, you can't restore it.
You apparently flashed the engineering abl through the qfil, according to the manual for unlocking the bootloader. This engineering abl is needed to get into bootloader mode (for fastboot has become active). After unlocking, you need to push back the native abl_a and abl_b, did you make their backups, according to the manual?)) In general, as far as I understand, the engineering abl, it is originally from the 850th model (in the bootloader, when the engineering abl is flashed, the displayed phone model changes), but it can be used to unlock it on the 820th, but since it was originally from the 850th, so the touch does not work. thats normal. finally. after you unlock bootloader push back the native abl_a and abl_b