Zump 390lm power problem

[oly]

just been away with my 390lm. tested it and wired to switched live.
nav started playing up saying it had lost nike power, then came back on and did this constantly for 5 days.
now i cant get it to power the nav at all.
ive tested the voltage on the pins on the mount, at first i got 5v. then nothing.
checked the fuse. ok
is it the nav or the power lead?

 

[Bumpkin]

How (i.e. what sort of connection) and where on the electrical system did you connect the power lead?

 

[oly]

Wired it to switch for GPS.
On a ducati