GPS wire routing

ISO4165:2001 (DIN/BMW/Hella/Merit/Powerlet) plugs are a poor design. I've found that the "center clips" in the outlet need to be bent inward toward each other, and it also helps to bend the circumferential contacts on your plug outward, in order to get firm contact. Of course, make sure you use something non-conducting to bend the center clips inward if the outlet has power.
 
Now you say that, I recall it didn't feel very positive when I plugged it in.
 
Mine powers fine, but I tapped the actual wiring under the cover. Same wires are being used to power my Denali DRL's. Use https://a.co/d/3lgubV4 for a good connection.
 
That's odd, they are wired up as standard. As a thought, could you plug your phone into the din / usb plug via a cable & see if it begins to charge? If no, then maybe check the fuse by the battery, can't recall properly but I think it's a 20amp fuse? Any case the fuse is identified on the cover. The bike will need to be running though. It's a switched socket & I'm not sure if it gets a supply without the bike running.
 
I had to go into the dealer yesterday for some tyres. I asked about the DIN socket and as @Einar suggested above, it was a poor contact inside the socket. The USB adaptor I have lights up blue when powered and it was flickering on and off. With a bit of adjustment with a screwdriver it is now working. It's live when the ignition is on. Engine doesn't need to be running.