Did I bleed my brakes wrong?

1988 Nissan 300zx. I replaced all but one caliper with new ones and just replaced the piston/seal on the one old one. I made a numb nut mistake of just letting all the brake fluid drain out of the car while I was working on the caliper, not smart. So with the calipers back on I would fill the brake fluid reservoir while I had someone pump on the brakes to pull the fluids back into the brake lines and when that was done I bled the brakes from the farthest to closest. First time ever doing this I had the person pump on the brakes and hold then I would open the valve, close and repeat. I did this for each caliper until airless clean brake fluid bled out. Now the part where I don't understand where I went wrong. When the car is OFF the brake pedal is pretty stiff but I can still press it to the floor and when the car is ON the brake pedal has no pressure what so ever like I can use my index finger to push it to the floor. Also the rear brakes are clamping onto the rotors as if I am applying brakes but the fronts are fine, I loosened the valves to see if there was built up pressure but nothing came out except a few little drops. I also heard some new sounds after all this like when ever I press on the brakes it makes a "click" sound somewhere in the center where the shifter is and I don't know if this is related but while I was pumping the brakes I heard a loud pop from the engine bay. I checked around where I heard the pop but didn't see any fluids dripping or anything. So what happened did I break something or what?

Thanks.