Tuning Condor 25 air leak

My buddy has a Condor 25. He recently put an upgrade from Talon Tunes. Think it was hammer spring, suppressor maybe something else. It was to help quiet the gun down. After he got it back togather he brought it down to my house to fill it back up with air. After it got up to pressure I released the pressure from the yong heng compressor and the air from the gun just ran right back out of the gun. Could the fill valve have gotten messed up somehow or any other ideas? He was gonna just order another fill valve. I thought I'd see if I could get help on here first. I searched for repairs on here to no luck. Thanks in advance.

JPW