PBJ happened to be not wrong and wrong
The screen the op showed is the test screen that requires the user to hear tones to then troubleshoot further. Unfortunately he has no tones, hence the check hardware. He could absolutely end up with chip/trace/board issues once he gets some semblance of sound working.
Yots is on the right path. MK1 had the sound pot, but mk2 doesnt. Another board would be helpful here to test the speakers/jamma harness.
For voltages, these types of boards can certainly be sensitive to variations, but that usually prevents booting in my experience.