Hello,My name is George.
I own a Phantom 2 V. 2.0 and have had it for about three months.
Recently it was acting funny, for instance, not responding to the controller. I waited a day or so before powering it back on, I do have a full battery if you are wondering. It does not respond to my remote.  I know it is connected because I can go into failsafe mode and the lights will flash yellow. Also, I can control my gimbal a little bit but it won't go up and down as much and makes funny noises when I do. Sometimes, I can get the motors running, usually I will arm it but nothing will happen, but I can't get enough power to lift off the ground. I have calibrated it, updated all the firmware.... I have done everything. I believe it could be a faulty transmitter or possibly a esc or electronic speed controll system. I have a warrenty but would not like to send it in just yet, just in case I can get it working before then.  When I plugged it into a PC, earlier, this is the first time this has happened, I got an error 27 alert meaning GPS interference. PLEASE HELP!!!!!
So the problem is,
transmitter: does not startup motors...usually..... when it does there is little power to the motors.
Phantom: motors dont start
Gimbal (H3-3D) Does not respond to up and down.

glataif,

Did you have any kind of hard landing or crash prior to this?
Did you get your Phantom wet in any way?
Are you in a restricted flying area by any chance?

Is the TX set to the correct mode ?,  it should be in mode 2 (set in the RC asst software)

Likelihood of your transmitter being the root cause is IMO pretty low.  
Any abnormal LED codes on your P2 when you try to start the motors?
How well do the sticks function when you look in the Phantom assistant software with your Phantom connected?

I have crashed before, but not recently. No unusual lights except for one earlier today which was yellow, red, red, red, then yellow when I tried to start the motors. All but one stick in P2 Vision Assitant software did not reach its limit although it came close to doing so. I kept my mode in mode 1. What does Mode 2 do? Also, I contacted DJI and they want me to send in my unit. Is this necessary?