Is there any way to recover a corrupted package? [SOLVED]

Ok, fully recovered I think!! Here is what I did, if anyone does the same mistake as me:

- Opened my broken package in SP4E - it works and it displays sufficient data
- Opened again in S4S the object I had started with ( Object -> Create 3D mesh)
- Only modified the obj definition file this time - fortunately I had not done many modifications on it, just the name, the tuning Id and the instance Id. I got those from S4PE. If you have an easy way to do it, you can also modify the instance Ids of the model, rig, slot, and footprint - S4S generates new ones each time it starts a new package, so they don't match, even when it's based on the same object. But I was working on 2 computers without easy means to share data, so I was copying stuff manually and could not be bothered to copy all that.
- Saved the package in S4S
- Then in S4PE exported the objdef file from the new package and reimported it in the old one (right click -> Replace on your OBJD). Then save
- As a result I have a package that opens successfully in S4S (yeay!!).
- The studio tab however does not display a mesh, and if you try to import one it crashes. So you need to update the model, rig, slot and footprint instance ids to the correct ones from your package (as I said, they were modified). After that switching to the studio tab yields another crash, but then when I reopened - TADAAAA all is there and all seems to work

I have not tested it in game yet, but I can see all my animations and tunings and states, etc, all the things I spent hours doing. So even if there are things to fix, they will be fixable.

P.S. Now that I think about it, I probably could have even exported the package without modifying anything in the obj def - and just update it afterwards, in the fixed package, like I did for the models, etc. Not tested, so can't be sure, but I don't see why not. It would make it all even simpler

BIG THANKS to qolygonal for the tip!