I am having this issue to which, whenever I slightly bend or tap the left and right surfaces by the mouse pad, the audio...

The Keyboard is held into the palm rest with plastic welds. Follow a disassembly guide for your Dell model until reaching a point where you can comfortably access the keyboard. The keyboard will be covered in a plastic layer to protect the internals from water. Remove that. Then you will be able to see where the keyboard is plastic welded onto the palm rest. I just used a soldering iron and carefully melted them, avoiding wires / cables. Then I could pull the keyboard off. Basically imagine instead of having screws to hold the keyboard in, they had plastic rods melted to hold it in place.