I recently bought a used Labradar, it also came with a remote battery pack.
I started having an issue with it not arming- it would shut off when I hit the ARM button the second time.
Phoned The people at Labradar and they told me to check and see if it worked with AA batteries and it did.
The gentleman on the other end of the phone then explained that the cord for the battery pack was too light
( it is not the one supplied with the Labradar) and if only only one or two filament wires are broken in those cheap cords it will not arm because it needs the full power.
This explains why many people go through so many of the cheap has station phone charging cords!
Picked up a better cord and the unit is working perfectly once again.
All it took was a phone call!
Cat