Excellent. let us know how it goes. BTW WhatsAPP is a known offender of battery drain for some users. Perhaps that is all that was killing yours. See how it works like you have it (fresh restore). If ok maybe get another backup without overwriting your complete backup, you can do this in iTunes if you rename the folder in your user directory (if Windows 7) C:\Users\xxx\AppData\Roaming\Apple Computer\MobileSync\Backup. May need to find it in other versions of windows or on a Mac. Rename the big long numeric folder to whatever maybe add 2012-1-17 to the front of it. Then run the backup from iTunes and it will create a new backup of current fresh state. You can see this afterwards in itunes when you select the restore, you will have 2 to choose from.
So now you have your complete backup with your score you want to keep and a backup of a fresh install. If all is ok you can try to restore your complete (with your score), remove the whatsapp app and see if it works. Worse case you can restore your fresh working backup if need be.
Honestly if you can live without all the previous stuff, keeping the fresh restore would be best. Good luck!