Second-hand P2V that fell into a pool, isn't flying correctly. Also, I am completely new..

Hello, fellow uav/drone/rc flier hobbiests. I was hoping some of you might have a bit of insight into this situation. I recently purchased a P2V, which, I was told, had crashed into a pool and isn't flying correctly. Before I go any further, I would just like to make it clear that I am completely new to all things drone/uav/rc. What I am looking for is a way to figure out what (if anything) is wrong, and how it can be fixed. Is there any diagnostic software? I was told that it might be the "controller boards" inside, which can be replaced fairly easily. Is there any way to determine whether it is one thing or another? I would like to figure out if it is the board or the important components (flight controller!) that is damaged. The best way I can describe it as someone who has only flown a (seemingly broken) uav one time, is that it was "shaky" when it was hovering. The wind was blowing at 6 km/h, but it seemed to be very unstable even when I wasn't touching the controller. I would really appreciate any information anybody might be able to provide. Sorry about the newb question. Thank you for your consideration.

 

Thanks for the reply. Yes, I have downloaded the drivers and software and calibrated it. I did both the basic and advanced calibration, both of which gave me a green checkmark. However, the flight is still very erratic.