It sounds like your /etc/fstab is using labels rather than the actual devices and the label doesn't correspond to the correct partition.
Boot in rescue mode, mount your / partition and edit /etc/fstab to use partitions rather than labels and it will probably boot then.
Redhat 8.0 Rescue mode
# Redhat links
RedHat Linux Manuals
Easier software management: apt4rpm
- Red Carpet
RedHat 8.0 Tips & Tricks
# Redhat 7.3 down configuration commands
leads to several configuration tools
# Redhat 7.3 up configuration commands
Configure X server: