FX Maverick failure to re-fill after degassing

Guys,
Though to share it here... I'm using a FX Maverick .22. Today I decided to empty the air-bottle fully and then refill. What I did was loosen the bottle halfway untill i hear the hiss. The hissing continued till the 1st pressure reads 0. I was happy and also made some dry fire to empty the plenum. So now it was good for air-ship.

The next was the disaster. I started to refill and found air is coming out from the fill-port. No matter what, it keeps coming out. I again put the compressor ON, made some air inside and bled the hose. While pressure dropped below 50bar, i could remove the hose, still hissing and air coming out but i instantly removed the bottle. I was sure that bottle valves are okey, as re-attaching the bottle, i found the hissing again for last leftover air. After close inspection and using some common sense, when i concluded that the air is coming out from the fill port, which is supposed to be an ONE-WAY UNF fill port, it became 2 way. Opening (unscrewing) the fill port I found the valve's O-ring is half inside, half outside. It was intact, but somehow lost it's rubberish temper. I also found grease there and later discovered the grease was also blocking the nozzles. I removed the grease, changed the O-ring and used some silicon oil instead of grease. gave some high pressure without bottle to clean the nozzle and then started to fill it. It worked like charm. Now waiting to see till morning if the air retains. I hope it will, and then all i will do is removing the bottle, opening the fill-port and give some thread-locker and re-install. I hope this will work.

Shared it here so someone else can solve their issues if same.
 
Update on this phenomena:

No matter what, don't let any water vapor to go. Get a real water separator (not that small foam beads) with your compressor and make sure, air source is also having less humidity. Because de-gassing was NEVER the cause of filler-inlet valve failure rather the water particle that changed the temper of rubber O-ring. Also I found the filler connector had rust inside (original FX parts though) and that rust when went inside while filling, that caused some issues with O-ring. O-ring MUST be clean as possible.

Finally I had to change the O-ring, added some silicon oil (I used ballistrol) and personally prefer using Loctite on threads. (But i avoided it now). 2 drops of oil for the fist time refill and did some firing, and then another filling and let it stay there for a night. First night the pressure got some changes but then finally there is no more visible changes.