1996 i30 parking - emergency brake stuck

[snick]

It's a 1996 Infiniti i30 (i30t). The master cylinder went out while driving. Using a combo of down shifting and the parking - emergency brake I drove the car home. Replaced the master cylinder and went for the first test drive. I found that something was dragging in the back. On cement it just was dragging, when I got back to my gravel driveway I found that the left rear wheel locked.

After playing around I found that the parking brake will not disengage on it's own. I can knock the parking brake level on the caliper to let it loose but if I pull the e-brake again it freezes up and I have to manually move the lever again.

I've never dealt with disk/rotor e-brake before. I'm used to the drum e-brake. In the service manual and looking at the car I'm not sure where to start. Is the return spring on the caliper supposed to release the e-brake? Just not sure If I should be looking at the return spring, the parking brake lever, or the caliper. With using the normal hydraulic brakes, the piston in the caliper releases fine. Not sure if there are other internal parts in the caliper that relate to the e-brake that could stick like this but not stick with using the hydraulics.

Thanks.