I dont have any experience with 2nd gens, but I'll try to help.
The Ebrake works on a cable based system. There are two brake cables that extend from the back of the brake handle, and run to the rear calipers. When you tighten the nut at the handle, you put more tension on the cable and make it engage sooner, or if its too tight, it will be engaged while the handle is fully down.
The cable runs to the caliper and is when actuated, it pulls a spring mechanism which mechanically engages the piston to press the pad onto the rotor. Dont quote me on this, I havent done much research on how an ebrakes force is actually applied.
If you have rear drum brakes, it may be similar in a drum brake setup, though I dont know.