If your laptop did not come with an OS. Did you install all the ASUS programs and drivers found on your Driver DVD? Yes I know you don't have a DVD player. Did your laptop come with a Driver USB? How did you install all the ASUS drivers and programs?
The Driver DVD for your laptop can be found with the below link. It's a German site (use translator if needed), the downloads are in English.
https://www.asustreiber.de/downloads/download/60-windows-10/830-ga502du-treiber-dvdDownload this Driver DVD ISO file, extract the ISO file, then right-click on the extracted ISO file and mount. Copy the results to a folder and rename the folder "eSupport". This would be what this laptop would have had installed with an OS.
Now go into the eSupport Folder and find the ASUS Installation Wizard (AsInsWiz.exe). Use this program to install all the original ASUS drivers and programs. Your microphone should now be discovered, and drivers assigned.
If this still doesn't work, make a copy of your eSupport Folder on a USB, then format your OS drive and reinstall Windows. Now BEFORE you start updating Windows, install your eSupport Folder and use the ASUS Installation Wizard to install all the original ASUS drivers and programs. Once that is done, reboot your laptop and allow Windows to update itself. Your microphone should now be seen in the Device Manager.
If there are any further questions look at my "Sticky" at the top of this sub-forum labeled "of your eSupport Folder before formating your OS drive!".
Removal of the back to your laptop would not void your warranty.
Good Luck
G752VSK, G75VW-3D, G51J, G1S
Homebuilt Windows Server