iCS g33 firing two shots on semi loose cylinder head overheating

[Grantcollins]

I bought an ics g33 new, when I got it it was shooting quite low fps on my crono about 245 fps. then when shooting in semi it would fire two shots on a single trigger pull. I put about 300 rounds through it on single and full and the pistol grip got really hot. It also sounds like it over winding when shooting inconsistent shots

So I open up the gearbox and notice that the cylinder head is real loose and literally falls out when trying to check for air compression, it does not fit the cylinder properly it just won't sit in there we'll enough
I put it back together and now I have NO compression what so ever

Anyone got any ideas about any of my above issues

I was running a 7.4v 2600mah lipo on a deans connector which I changed.

I would greatly appreciate any help

Cheers