Update: After finding the time to speak with a PCB specialist at my office, I’ve done some work overhauling this thing. The reason the board was so toasted is that I was using a silver solder, which has a high melting temperature. I’m now using a lead solder (in a fume hood) which has a much lower melting point.
I’ve also bought and secured a new diode to replace the one was that ripped off the board. (The PCB specialist helped me make a new connecting terminal! )
As for the problems I was having, I disconnected the LEDs to make sure they weren’t causing any problems, and secured screw terminals to the board to prevent further heat damage. I’ve also replaced the speaker and wires connecting to it.
Here’s a video showing the audio problem I’m having. I’m using the audio files recommended in the tutorial (the ones here). As I mentioned previously, the sound “vibrates” and is quiet. The current speaker is Digikey p/n 433-1147-ND, though I’ve tried a few others as well that I bought for this project.
Things I’ve tried:
-Replacing the speaker and wires (currently 24 AWG multi-strand wires)
-Replacing the audio files
-Changing the audio volume in the program
-Disconnecting the LEDs (to prevent excess power drain from the two 18650 3.6V batteries)
-Resoldering speaker / wire connections
-Resoldering the screw terminals to the speaker
-Resoldering the screw terminals to the batteries
Any ideas what might be happening?