When I was installing my head unit. I checked to see if it switched on, but it wouldnt, but the antenna would go all the way up. After tinkering for ages and finding out my own silly mistake, i found the wire to the power antenna and then found a good earth tried it again and bam all sweet.
Did you install it yourself?
Dash takes 2 mins tops to pull out. And that is if youre using one hand haha.
If you didnt do it yourself I would take it back!
If you did do it yourself unplug the antenna wire going into the headunit. Youre problem definately lies with where the antenna has been plugged into the headunit, seeing as its giving it a constant voltage which is driving the antenna motor!