I had to add a module so the BrakeRite system would identify the signal from the truck (2010 Chevy duramax)
Worked fine then blew a 40amp fuse replaced it then it worked fine on a 2hr pull until I got into stop and go traffiic where I lost brakes again
Checked the same fuse and its good, checked that I DO have power to the connection at the bumper connection and there IS power to the prong at the bumper plug.
All the trailer lights work just fine

Check the wiring harness directly before the trailer 7-wire round plug. GMs have had a lot of failures there. The harness makes a tight bend and is fairly exposed to strike damage, I had to replace the actual connector on my Ford as well.

Remember, you have two "hots" for the electrical brake system to activate. The 12V constant hot, and the +Voltage variable hot that ranges in +Voltage depending on how hard your brake controller is telling the trailer to brake. You will probably need two people to check this.

Last, on your Myco, you should have a junction box that you can open and check the voltages on the trailer before they are delivered to the EoH actuator.
If you are getting the right voltages there, you probably have a bad EoH actuator. These also can go bad, especially if they get wet. I do not believe the electronics are serviceable either; entire replacement but BrakeRite will know for certain.

The pigtail on my 2005ish Myco had pretty much gone do poop over time as well when I acquired the trailer a few years ago. I also replaced this entirely with a new pigtail from www.championtrailerparts.com . I did have to pin out each wire as their colors and locations did not jive with Ford and Myco for my application.

I just had a problem with my Duramax 2500, had to bring it into Chevy and replace the Brake Actuators or brake controller, they said it was working fine. Well it was not working with electric over hydrolic brakes I found out after looking to see if anyone else had problem on Duramax forum. So I bought the Prodigy and had it installed and work great.

Turned out to be a bad ground

I had same issue yesterday I installed the module on my trailer because my brand new gmc Sierra Denali with the built in controller will not work with my eoh brakes. I installed the module to the blue and white wires and it worked 1 time then nothiing? Where is the 40amp fuse you blew please?