Assumimg that you do not have your pc and the gauge both connected to the datakey and your gauge reads that it has 7.5 volts.
My suggestion would be to call AIM support with the gauge, datakey and GPS module in hand. If your equipment has to go in for repair, AIM’s turn around is usually fairing quick.
Another thought. Are you using a two port hub to connect your GPS to the M4?
LAD Specialties customer / tony kart / rotax / kt100