Harvey51 wrote:
There is no "source" button. No USB port or input jack of any kind. I did find a pair of unconnected audio wires coming out the back that were labeled as audio output for an amplifier. I guess it is a cheapo vehicle radio.
Try a long press of the power button, too. On my (no-name) replacement radio, a quick press simply puts it in mute mode, while a longer press turns it fully off. Current consumption when off is properly low (certainly not a significant fraction of an ampere).
It's also conceivable that the power consumption will go down after several seconds or a minute or so, if perchance you measured it immediately.