If your phone isn't charging correctly, the microphone isn't working, or the GPS is drifting, the Hidden Menu contains a "Device Test" suite. Here, you can manually trigger sensors and hardware components to diagnose a hardware failure without taking the phone apart.
: Download only from trusted Android development communities. Keep a backup of your stock ROM via LGUP before tinkering. And if you truly want full control, look into unlocking the bootloader and installing a custom ROM like LineageOS for the V20 (which has its own hidden menu built into the dialer). hidden menu call 1.7 apk lg ls992
The "1.7" refers to a specific version of the app that was widely circulated and found to be stable for devices running the Android versions typical of the LS992 (Android 6.0 Marshmallow and Android 7.0 Nougat). If your phone isn't charging correctly, the microphone