I assume the second one is reversed for ease of reading.
I didn’t catch it earlier, but it looks like there is a resistor in the speaker loop. @MLXXXp did testing that established the speaker resistance alone would be sufficient for protection. What value will that resistor be? – and what will the larger speaker be, since it might have a different resistance?
It looks like an “Arduboy” label is sitting where the speaker used to be. I’m figuring that the speaker connects to the two square pad just up and to the right of the ATmega? But where does the speaker sit?