My  grandsons A7 microphone level appears to be very low.

Using the sound recorder I have to shout in order to pick up any sound.
other than that just crackles.

I have tried playing with the mic settings in hardware test/audio/normal/mic in engineers mode. no difference,
but not really sure what im doing.

Have opened back but see no obvious problems, mic is hidden anyway

I recently had to resolder 1 usb pin (solder joint had cracked after it was dropped)

BTW, i have one to, great phone:)

Hi there! Unfortunately your issue looks hardware related. You'll have to replace the microphone by yourself, as I think the seller won't Honor warranty terms (you opened it).