Brakes won't retract... Options

[amphiduck]

So I just put all four calipers back on my car, filled the reservoir with fluid and pumped the pedal a few times to see if there were any leaks around the pistons. The system is tight, no leaks anywhere. I started bleeding the pedals in the order given by Haynes, and now all the rotors won't spin because the pistons won't retract and the brake pedal barely moves. What gives? I feel like I'm making a novice mistake somewhere.

Thanks in advance.

[Tom]

Try opening the bleed valve a small amount on one wheel only and see if pressure bleeds off on that wheel. If it does and the wheel turns more freely, how about the other wheels? If the above wheel turns freely now, you may have the old rubber hose problem, the internal passage swells up and won't let pressure bleed off. If they all turn freely after bleeding only one wheel, you have something wrong with the master cylinder.
Tom