Ugh, that sucks. Is there a chance that you used the openHABian backup/restore at some point? If so, there may be a zip file on the SD card that you can grab and use as the basis for restoring a new system. If not, maybe you can make one and trick the new system into restoring from it.
The zip backup contains copies of your conf and userdata directories. The first one has your text config files, and the second one has your JSON databases. There’s also a file called backup.properties. Mine has this content:
version=3.1.0
timestamp=21_11_20-20_31_58
user=openhab
group=openhab
In theory, you could make a zip file with those two directories and this file, and then use it to restore after you set up a new openHABian (using the sudo-openhabian backup/restore command). I’m just guessing at this, though. No idea if it’ll work.
Once you’re back up and running, you might want to look into doing your backups with the Amanda and disk-mirroring options built into openHABian. I periodically take my SD card out and use Win32DiskImager to save a copy so that I can produce a new card at any time. I just like having it stored on a separate hard drive.
If you want to add a UPS in the future, I wrote a guide for connecting it to OH with Network UPS Tools.
Good luck!