Note that Blackview device navigation supports GPS+GLONASS+BEIDOU.
There is no option to choose which to use.
Depending on your current location, your googlemaps or any other map app will automatically detect and choose which one to use.
There are 35 BeiDou satellites, 31 GPS and 24 GLONASS satellites currently in orbit.
How to access Gyro Calibration Tool:
1: You will need a credit card for covering the proximity sensor (as shown in Video)
2: Turn on the device
3: Go to Call App
<Steps below are accompanied by pictures for easy reference>
4: Enter engineering code *#87#
5: Select MMI1
6: Select Single Test
7: Scroll down the menu and select Gyro Calibration to start calibration.
8: Please make sure that the phone stays on horizontal plane during the calibration process without any movement.