Instead, I get a 503 Service not available error. This happened after a sudden loss of power (power went out in neigborhood). The ad blocking and CLI still works.
As you already noticed, your PHP install is severely broken:
*** [ DIAGNOSING ]: php version
[✗] php version could not be detected.
You can try to reinstall PHP, but apparently something else might be broken in your system.
If you can't reinstall PHP, my suggestion is to reinstall your OS and start fresh.
If you are not able to create a teleporter file, you can copy the files in /etc/pihole as a last resort. Later you can use this files as a base to edit the config of your new installation.
Yeah, I think I will reinstall onto a new SD. I think the power loss might have corrupted the file system somehow. What should I do with the files in /etc/pihole when I reinstall. Just copy them over?
I think you can create the directory with the old files and install Pi-hole. I think Pi-hole will overwrite some files, but it will keep your database and setupVars.conf.
To be safe, keep a copy of the files in case this goes wrong.