Hello,
i have a problem with an used DJI Phantom 3 std. Right after turning it on, when there is no GPS fix yet, the map shows my position and I can arm the engines.
As soon as the GPS got fix and the message "Ready to Go (GPS)" appears in status bar of DJI GO application, the map moves over the Atlantic Ocean (GPS position 0 / 0)
and when I try to arm the engines, I get a message:
"Aircraft in no-fly zone"
Of course I'm not in a restricted area (I've checked it)
Also, when trying to save the drone's position as a base from the menu, the following message appears:
"Aircraft GPS signal weak. Home point is not updated" even though status LEDs flash green.  
The DJI GO app reports firmware 1.9.20.
What could it be? GPS damage?

I've found broken wire on motherboard, between processor's UART8_Tx  and GPS connector (pin Rx). So GPS was not programmed properly by controller. After soldering wire bypassing broken path everything works as expected.