Your version of u-boot is too old, this should get things to a more sane state…
sudo apt update
sudo apt install --only-upgrade bb-u-boot-beagleboneai64 bb-customizations
sudo systemctl enable bb-symlinks.service
sudo /opt/u-boot/bb-u-boot-beagleboneai64/install-microsd.sh
sudo /opt/u-boot/bb-u-boot-beagleboneai64/install-emmc.sh
sudo reboot
Regards,