Cannot Access wp-admin

Seems like you tried a lot of things, sorry you’re stuck like this.
You didn’t mention anything about the database, though – have you also tried importing a whole new DB? An usermeta issue might explain this.

I’d try deleting the database (while backing it up first) and renaming the plugin folder to something like “_plugins” to make sure WP won’t see them.

If it starts the setup process, great – you’ll likely have the wp-admin. From there, rename the plugin folder and start troubleshooting the database.
If it doesn’t, I’d back everything up and nuke it. Start with a fresh WP install and begin movings things slowly, one at a time.

If a fresh WP install won’t work either, I’d start troubleshooting the server (or rebuilding it).