Working on it right now. I removed the Weapon_Grenade.zip from my add-ons folder and the backup.cs is working fine, except that for some reason when the backup grenade explodes, it's in the wrong spot.
EDIT: Not sure what happened when the explosion was in the wrong spot but I can't get this to happen again. Re-releasing in the next 5 minutes.
EDIT: Updated. I'll edit the first post again soon.