Log in to SCDB.info with your access key and go to product page for Alpine INE-W970BT & INE-W990BT. Load the file alpine-ine-w9x0bt.zip to your PC.
Connect an empty USB stick to INE-W970BT/INE-W990BT (formatted as FAT32).
Power the unit on by turning on the ignition.
Note: The “Go!” button will only be selectable if a USB stick is connected.