Hi. I just purchased my new iPhone 5s yesterday. I noticed using it today that while the Volume Down button works, the Volume Up button is not responsive. I have tried resetting the phone, toggling the buttons, updating my phone, resetting it to factory settings, as well as Assistive Touch (while it fixes the volume, the button still remains unresponsive after use). Is there any other tips for getting it working again, or is this an issue I will have to take back in to the store for repairs?