You need to sign your friend out of the Xbox Live account he was using and then shut down the controller by unplugging it from the console. I hope this helps your issue.
Sorry that hear that your kill streak was ended but it sounds like the motors that cause vibration are dead. You can follow our Vibration Motor Replacement guide to once again feel the impact of a grenade.
Hi Aaron, Your controller not connecting could be due to multiple issues. Your cable could be torn or the connection in the controller could be loose or disconnected. Follow our Torn/Frayed Cable Replacement guide to fix your controller.