We have released a new STV that fixes the problem with the microSD Cards written with a Mac. It's available here:
https://www.arcade-projects.com/threads/new-version-new-stv-multi-dark-knight-edition.24224/
We have released a new CPS1 Firmware, that fixes the problem with the microSD Cards written with a Mac. It's available here:
https://www.arcade-projects.com/threads/cps1-multi-support-thread.21550/
the fact that no sound comes out, makes me think that the problem might be with the microSD or the reset. About the microSD can you show us what you are using? Did you try with a different one?
You can also keep pressed the service button before powering up so a special service menu will show up and you can test the motherboard. The fact that it worked with one game doesnt mean it's working well. I've seen it too many times.