Master cylinder replacement

You didn't do anything wrong. The master cylinder is defective.

There's a whole lot easier way to bleed the system. If the air is out now and you have a good pedal, just loosen the steel lines, pull the master cylinder off the booster, tug it upward to tip the lines, then no fluid will run out of them.

Remove the lines, bench bleed the new master cylinder, hook the lines to it, then use it as a handle to push the lines back down so you can bolt it to the booster. Have a helper slowly push the pedal half way to the floor. When he does you'll see air bubbles comes out of the connections. Snug the lines, THEN tell him to release the pedal. Open one line and have him push the pedal again, never ever more than half way to the floor. It should take him about 20 seconds to go that far. Tighten the fitting, then do the same to the other line. Now if there's any air bubbles left in the lines, push the pedal once more slowly, then let it pop back like normal. As the fluid rushes back to the reservoir it will wash any air bubbles with it. No need to bleed the wheels.