[Help] stuck on v74, not updating on LG G4

so I've had the notorious Snapchat problem, and I've tried numerous times to flash the uninstall zip with flashfire, and when that failed, i flashed the update 79 and 80 zips which both failed.

I'm fairly sure I'm doing things correctly, but they're not working.

I guess the last resort would be to flash the kdz and re root everything?

any help is seriously appreciated