Advanced root problems I am having problems rooting my device after a friend unrooted it.
Now, if this was a pure simple case, it'd already be solved, but:


I can only used soft-roots, like Kingo root.
My "friend" decided to change my android version number and model number before the unroot, making these soft-roots not work.
My device will cease to function if I SIM unlock and bootload. Don't know why.


Please help. I really want to sell my device, but cannot.

-EDIT-
Well, FTP failed, as did using ADB to pull, edit, and push the file back on.
Somehow managed to get king root to work...

King root was the original rooting tools I used, and after the change in the build.prop it stopped working. It seems be fine now, tough.