First of all, thanks!!
I just tested and the pinout on the buttons is as follows (Left-Right, 1-5)
Gnd-2-1-4-3
I did notice the PCB is printed as GD A3 A2 A1 A0 GD, safe to assume that A0 goes to Button 1, A1 goes to Button 2, A2 goes to Button 3 and A3 goes to Button 4?
The buzzer part...