I'm suspecting your directional valve may be off center thereby blocking the fluid to the calipers. The directional valve is often mis labeled as a proportioning valve. It's job is to block off 1/2 of the system when it detects a loss of pressure in that 1/2 of the system. It also triggers the brake warning light when the valve goes off center.

You can try having a helper put pressure on the pedal. Crack the port going to the front brakes, you should detect fluid being displaced under pressure. Tighten the fitting before allowing the pedal to come back up.

If that checks good move to one of the front output lines and repeat.

Continue through the system until you find the restriction.