Brakes Brake Gurus: Need Some Help!

Trying to finish up the brake job from hell on the daughter's boyfriend's 04 Mach I. He had to paint the calipers (don't blame him, just wish he would have kept it simple; the vert's been living outside while he takes up my garage space).

Anyway, everything is reassembled. Rear brakes bled fine. Did probably 20-25 cycles on the PS front, with NO fluid flowing out. Went over to the DS front, and got a steady flow with no air in probably 6-8 cycles. Went back to PS front, and still no fluid.

I had almost no leaking of the front lines while the calipers were disconnected.

Not sure if it helps any, but the PS front pistons were completely seized. Like, so bad you had to put a punch through the hole for the brake line and pound the piston out. (yes, we replaced the caliper). Could the line be plugged? Where should I start checking? If this had been plugged before, would that have caused the piston to seize? If the pistons had seized and no fluid were flowing to that PS front brake, would the car still have braked in a straight line, or would it have been obvious that we weren't getting braking on the RF (I would assume it would be obvious, but looking for anything to make sense of this now).

Thoughts?

Update: Went back out today (previous was results from last night), pumped it up, and got fluid flowing, with a LOT of air. Bled all the air out, getting nice, clear fluid flowing. But the PS front brakes won't release (DS front and both rears rotating fine). Getting ready to do that search, but if anyone knows what to do next, feel free to chime in!

Pulled the canon plug to the ABS unit; saw on some posts that doing that would release it if I had an HCU problem. It didn't release anything. DS still works fine. ???


UPDATE AGAIN: Pulled the brake hose; that relieved the pressure and allowed the pistons to retract. So, looks like I need to replace a line.