To Fix a non booting manjaro system, Boot from manjaro sytem from usb and run the below mentioned CLI Linux commands in terminal to solve manjaro boot problems encountered after recent update.
mount /dev/sda10 /mnt
mount -t proc proc proc/
mount --rbind /sys sys/
mount --rbind /dev dev/
mount --rbind /run run/
sudo pacman -Syyu
Don’t forget to Replace /dev/sda10 with partition number on which your manjaro system is installed, if you’re not sure about partition number, run ‘os-prober’ command.
Hope it helps, and leave comments if still facing any issues after this steps.