HFS-3 power issue troubleshooting

[Onieffect]

Good morning

Seems like a common issue, no power to gauge ( maybe even to conrtoller no leds light up ). Im following the start up procedure but getting no LEDS. Ive made sure that the connectors are seating correctly into the controller. The fuse looks good. Read all i can but havent gotten anywhere.

Just Hoping for some troubleshooting info. Can anyone explain to me in simpleish terms how to troubleshoot this. Hopfully someone can chime in and say that the red wire on the grey harness needs to see 12v+ and its just a battery being sillly.

This is how i have my car set up ( 90 mazda miata )

power connector
red - 12v turned on with accessories. Tested 11.8V at connector to controller
black and white - go to ground with ecu / wideband


Grey ECU connector
Red - Spliced into my fuel injector harness on the positive side. Sees 11.8V at connector to controller
Green - negative side of fuel injector harness
Pink - Map switching output from Megasquirt 2v3

Gauge cable plugged in both ends firmly
Gauge button depressed

Cheers
Scott