Since I don't have a backup of OMV5:
An ounce of prevention is worth a pound of cure.
Backing up an SD card is stupid easy, but you have to do it before it breaks, not after. This is a really good and simple backup tutorial for all three platforms:
There may be a way to do what you want (I don’t think so) but it will be kind of like cutting off a leg to get rid of that annoying limp. Just saying. Sorry.