If it's an stfs invalid error then in scientific terms: the container your save sits in is fucked.
For some reason dark souls save modding can be as delicate as IVF, the only thing i've known to be more tempermental is a profile after gpd modding.
If you have a backup before the problem hold it tight and keep it safe, then make a copy of it and inject your modded save into that, rehash&resign and try that.
In the event you don't have a backup please take a moment to slap yourself on my behalf, then hop on your xbox, delete the corrupt savedata clean off the drive, you want it to generate a new container so make a new save and extract it to your pc.
Now it's time to operate, open up the new save in modio, bring up the contents and replace the save inside the new Drak0005 with your modded one you extracted from your old saves container, rehash&resign and pop it back on the xbox, it should be stable now.
In summary you want to replace the contents of a new Drak0005 container with your modded save from your old, now broken one; Think of it like a brain transplant.
I've done this several times before, the success rate is fairly high. It's easy to do but rather difficult to explain, think of it as a test of competence