These units are not meant to run on battery.
They need to be constantly plugged into a cigarette lighter via provided adapter.
You can test if this is at fault by simply connecting a USB-A to mini (not Micro) USB-B port from one end (the A end) to your in-wall cell phone charger, and the other end to the mini port on your GPS. If it powers up, then its the cigarette adapter. If not, it is likely your battery.
For Reference:
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