If it's completely dead, make sure it's connected to a reliable power source. Try another car.
See Troubleshooting (click here). If it still fails to function, follow these instructions to obtain factory service.
Return your Valentine One and both power cords and lighter adapter (don't send the mounts) to:
10280 Alliance Road
Cincinnati, Ohio 45242-4710
your unit prepaid and insured, in its original packaging or something
equally protective. You are responsible for your Valentine One
until it is in our hands, so insist on a proof-of-delivery receipt.
Along with your Valentine One, please enclose the following: