phpMyAdmin is temporarily unavailable because mod_authnz_external was broken by upgrade to Apache 2.4.20. There is an unresolved symbol and so the module can not load.
Apache 2.4.20 made changes to the API that require modules to use ap_get_useragent_host instead of ap_get_remote_host function. Just changing the function name didn’t suffice, apparently arguments are different but I haven’t figured out where this is documented yet.
Further complicating matters is the fact that Jon Wolter, the maintainer of this package, died of influenza complications in July of 2015 and as near as I can tell there is no current maintainer. I have written to the maintainers of the version for 2.0 Apache hoping they can either point me to the new, if there is one, maintainer or help me to make the necessary modifications.
In the meantime, if you have to manually manipulate your MySQL database, you can do so using the mysql client on our shell servers.