KWC CO2 Desert Eagle .50AE issues please help

[xblazexupx]

I bought a Kwc desert eagle blowback the other day (co2 powered) and at first everything seemed fine. After about half a canister of co2 though the gun suddenly started to misfire, the magazine wasn't empty and there was nothing jammed in the barrel, I took a coupke more shots then it did something weird, where it felt like it was trying to shoot full auto, then it just stopped firing completely like it was out of co2. When I went to release the canister it started releasing the other half of the canister of co2. I tightened it back up before it could release it all and when I put it back in the gun it shot a couple bbs and then ultimately needed to be cocked every time i wanted to shoot it. What could cause this? The magazine doesn't leak at all and there's no hissing sound.