With the provided information, there is no clues.
The following seems obvious
- The system’s firmware can be loaded
- A live ISO loads
- Manjaro boot menu loads (grub)
Since the grub menu is shown - I am guessing you dual booting other operating systems.
Have you tried to switch to another TTY? Ctrl+Alt+F4, what happens?
If you get a prompt then your issue is related to graphics, and since your topic is tagged with xfce, I am thinking you are using Nvidia GPU.
If you can sign on to the system using a TTY then please provide the link from the following command
inxi -Fc0 | curl -F'file=@-' https://0x0.st
Make a note of the link and provide it for system information reference.
If you can only access the system using a live ISO, then please follow the guide to enter a chroot environment and inside the chroot run the above command.