please check my answers below:
I can't seem to start a new thread as I've just signed up.
Not because of that; you couldn't create new topics in the "Tidings" forum where you've initially created a reply. This forum is only for admins (me), it's highly moderated 'cause its threads appear in RSS. You could create new threads in any other forum except FAQ. Your posts will be moved to the Specific forum after we close your question.
Do you know what it might entail to get it back up even as display only? Like what sql version of db or anything else?
For your purpose, you just need the backup of your forums mySQL database, the most recent one. Do you have it?
Do you have backups of old versions of miniBB I can download?
For security reasons, we do not host earlier versions of miniBB, and work only with the latest version. But the old version is not what you need actually.
You have to restore your database from backup, making it accessible online. Then you have to upgrade it following the miniBB's Updating guide
and referencing only Database updates, then install the current version of miniBB and connect it to this database in setup_options.php
Further is up to you — you could make all forums read-only, adjust fonts/colors/top logo etc. — just not sure what you've had previously, what add-ons were installed etc.
I could also provide my paid service in restoring your forum if at least
you have its Database backup; scripts and templates would be also ideal to have...