Hello and welcome,
so is an asus laptop and the video seems to have been made for
Well, we can’t be sure what else have you done to your system, so i see two options:
- follow this to recover your install [HowTo] Resolve an unbootable Manjaro (black screen, login failed, cant boot, etc)
- start from scratch and if you have issues that want to fix, share some information about your system as explained here [HowTo] Provide System Information and someone will help you out, or point you in the right direction.