Looks like the servo controlling the cam tilt has either seized up or otherwise failed. Some people have found they are able to get it over a 'sticking point' and moving again by hand manipulation, but if you don't want to try that, or that doesn't work for you, that servo is probably broken.
So your options are to either phone Yuneec in your country and get an RMA number to return it for a fix (you don't say if you are in warranty, or if this was the result of a crash), which will either be charged or not, depending on circumstances. Or, if you are out of warranty and feel up to the task, you can try and replace that servo (people usually recommend replacing with a metal gear version) and fix it yourself. If that seems too much hassle, there are drone repair shops that could possibly do this for you, but without knowing even which country you are in it is difficult to advise specifically.
