Pixhawk V6X FMU LED

Hello. I need some help. I am using Pixhawk V6X flight controller and Neo 3 M9N GPS in my quadcopter. When I armed at starting my drone make stable flight up to 40 m. But after that it get disarmed from 15m height. But it not cause any external damage to the hardware. After that when I reconnect power supply my GPS and flight controller not working and when I connect it with Mission Planner it shows message Config error and then reboot. As I am flying my drone in College campus which is a government Institute and comes under Yellow zone hence may be my GPS get locked. Also there is another interesting thing is that when I am connecting Pixhawk with power supply its FMU LED is Blinking at very fast rate for around 4 seconds in blue color and then goes off. I cant understand what it is indicating. Please give me solution how can I start my GPS and flight controller again.
Thank You.