Why My GPS has no signal or no signal after use for a period?

1). Restart the radio or reset the radio by pressing the small hole remarked “RES” in several seconds

2). Re-install the gps map app or other map apps, such as google map, here, etc

3). Re-install the system

4). Reconnect the GPS Antenna, put it in the better position to accept the signal.

5). Recovery into the factory set in the system set up

6). Put the GPS Antenna on the top of the dashboard, not inside the dashboard if work

7). Change to another new gps antenna if work or not, sometimes the antenna’s internal pin maybe broken during connect to the radio.