Chainsaw Repair

I just unboxed this 455 Rancher I bought from an Amazon dealer. I put in Huskvarna 50:1 premix fuel. For 2 days I couldn't get it to start at all, but gave it a rest and kept trying. Today I got it to start in fast idle- resetting the idle with the choke, then starting without choke. But as soon as I open the throttle to take it to regular idle speed, it conks out every time. I start it with the chain brake engaged. The decompression valve, alhthough it sticks a little, does pop out. But it won't even rev when I hit the throttle, just stops. Does anyone have any ideas as to what this could be? Should I return the saw?

If you are not comfortable with adjusting the carb or tearing into it a bit. I would try your local Husqvarna dealer or send it back