Hello, I’m Nathan, and I’ll be assisting you today.
Sorry to hear that you’re having trouble with this but I’ll do my best to help you out.
Have you tried updating the firmware, or even charging via usb from the computer?
I'm not sure what you mean by "collar"?
I'm sorry I misunderstood, I thought you meant something to do with the cord itself.
The firmware would be on the gps unit, if it wont' connect even after that and still flashes though that points to a hardware issue in the transmitter (collar) unit, which may have had some water infiltration or other physical damage.