I did get mine off the ground soon after I opened this topic and we figured out the problem. The problem turned out to be that I had the Pusher and Puller propellers in the wrong positions on the arducopter. I had pullers where the pushers should be and vice versa. The one particular diagram I was looking at in the wiki manual was incorrect (it was immediately corrected after we discovered this). After switching my propeller positions, I was able to fly, and I've been flying ever since. During the course of my corrective action, I also re-calibrated the ESC/motors.
I, too, am in the mountains, but the Blue Ridge Mountains (North Carolina), so my elevation is 2680 FEET rather than meters, which obviously isn't as high as you. I remember reading about other people flying arducopters at high elevation, so I don't think that's your problem, but you might want to do a search on the forum for "elevation", etc. By the way, I've only been to Colombia briefly on a bird watching expedition, but I love it. Beautiful country.
The easiest way to test the propellers is to spin each up up and feel which way the air flows.
@Taylor: Mistakenly installing the pusher and tractor props would not be that easy to diagnose just by feeling the airflow... it just wouldn't be optimized and adequate for flight.
(many of us did the same on our EZStars, and knew to feel the airflow... just had the wrong prop with the wrong airfoil curve to them)
Well whenever I feel the airflow, it's pretty obvious which side is pushing out more air.
Sure, but a correct prop pushes a lot more air than a pusher or a tractor on backwards, so just changing the ESC wire and therefore the direction of the motor doesn't always work, if you've messed up the right prop.
(they can both be made to push air in the same direction, but if the curve of the airfoil is reversed, you don't get the correct amount)
Both props move the air, but not the same volume.
Thanks for the advise..
Problem solved that way.