racketboy.com

I am having No sound issue on my gbm both on Headphones and speaker i can hear the volume ticks but there is no game sound ‘ is there any sound schematics available or any known broken parts which i can check i already changed the capacitor near the volume buttons.

That is weird. I was going to ask if it does that on GB &GBA carts (different pins for PCM & chiptune sound), but being a micro, that's not possible to test.
Normally, I'd suggest just installing one of Helder's amplifier bypass flex mods, but I don't think they are compatible with a micro.
I'm stumped.