@stephenw10 I managed to fix the problem, but it seemed haphazardly. I tried installing pfSense 2.6 by DVD only to realize that the previous memstick method did install the firewall OS despite no OS found rebooting the computer. Then, booting from the DVD would start and hung on synchronizing user. So, I made sure that the bios were set to legacy mode and CAS was disabled then booted the computer. This time it hung on CSM; so, I powered off the computer and reboot again and select single user mode and created the file as you had instructed:
echo 'kern.geom.part.mbr.enforce_chs=1' >> /boot/loader.conf.local
It then completed the boot up, and I could restore backup configuration. We'll upgrade to version 22..5 when my friend return from vacation. Thank you Steve.