Hi. My hardwired DR750 is failing to power up after I turn ignition off for example when I stop at the gas station to pump the gas. When I start the car up DR750 will not power up. I need to unplug power plug and plug it back to power it up. When car sits for few hours DR750 will power up when I turn ignition ON. If I turn ignition off and back on it will not power up. What could be the problem?