How do i reset the GMC Terrain radio?

The easiest way to reset the GMC Terrain radio is likely to disconnect the negative terminal from the battery for a period of 15 or more minutes. Press and hold the power button on the head unit to ensure that all stored voltage is discharged, and then wait. If You have a modern model year of the Terrain fitted with an Intellilink head unit, You can simply reset the unit by navigating to "SETTINGS" from Your home screen. Next, navigate to RETURN TO FACTORY SETTINGS, where You'll see three options. The two relevant to You are RESTORE VEHICLE SETTINGS or RESTORE RADIO SETTINGS. Select whichever one You prefer (radio is limited to the radio, whereas vehicle also includes Your trip counter, etc), and confirm to reset.