Only one brake working on a chevy S-10

So my brother and myself have had to do two different brake jobs on my Chevy S-10. The first job consisted of replacing the calipers on the rears brakes, both driver and passenger, which went off without any snags. Then the other day I was driving and I had a brake line blow out, this time in the front driver’s side. So again my brother came and helped with the replacement of the brake line from the caliper to the mater cylinder. after getting this all together we tried the brakes and there was absolutely no pedal to the brakes. So we checked every line and there were some leaks at nuts and we tightened them, fixing all leaks. So we tried the brakes out in the driveway giving the truck a little bit of gas and then hitting the brakes. Doing this we found out that only one of the four brakes are working, since it was locking up and the other three were not. I believe that this issue might be a master cylinder problem, but am not sure. Any advise on the matter would be helpful

What year model? Is it 4 wheel ABS or rear ABS? Is the ABS or BRAKE light on? Is the pedal high and hard with the engine running? A master cylinder forces fluid out at high pressure when it is working properly. Remove the lines from the master cylinder and plug the outlets. Pump the pedal repeatedly to bleed the air up into the reservoir and then, when the pedal is near the top press it hard and see if it holds. While continuing to press the pedal have someone open first one and then the other plug, watching for pressure to be released. If the master cylinder can make and hold pressure it is working.

This is a silly question maybe, but did you bleed the brakes to get air out of the lines after replacing the blown brake line?

Yes all lines were bleed in triplicate. The reservoir is filled to the proper amount.