Ran mount commands in live usb on wrong partition. Partition now mounted in other OS

Question

I've done something rather dumb.

I started with an installation of Ubuntu Studio 18.10 as the sole OS on my ThinkPad. I use that OS for some creative endeavors. I am also a (jr.) developer and wanted a separate OS on this same device for separation of concerns sorts of reasons (i.e. backup to my work laptop). I've used Linux Mint previously and decided to return to it for my planned dual boot.

Everything went fine until after install when upon reboot I was met with an (initramfs) prompt. Running exit command at the prompt gave me ALERT! UUID=BEDD-A8D1 does not exist. Dropping to a shell!. It was long before I arrived at this old post on this very forum where a user had had the very same problem.

I must have been too exited upon reading the accepted solution because I didn't read any further, rebooted into the live usb and entered the solution commands verbatim. Then rebooting again I met the same (initramfs) prompt and UUID error. Revisiting the post linked above, I read a little further where another user helpfully posted a reminder that sda1 isn't necessarily where you're install is. And sure enough, I remembered setting up the partition on my drive and the fact that my Linux Mint install was on sda5.

Just to double check that it wasn't already too late, I booted up the live usb again and ran the solution commands again, this time targeting what used to be the correct partition. And it was too late; only sda1 existed anymore.

I then booted into my original Ubuntu Studio install to survey damages. On login desktop icon style and size (2-3x!) were altered and on the desktop was my partition mounted as a drive. Inside are all the files of my Mint install (doh!). Nothing else appears affected (I'm on it now).

So, I have no idea how to fix this or even what to search for to help. I'm sure I can unmount the volume, but what happens to my Mint install? Can it be remounted to sda5? Are there other implications to this faux pas that I should investigate?

Help me, Ask Ubuntu, you're my only hope.