Originally Posted by ICEknight
Speaking of test modes, when I was little I found a sound test of sorts in the first Konami TMNT LCD handheld, which would play every sound one after the other in a loop. You can easily access it by fiddling with the batteries so that there's just a brief power cut, but there may be a more official way to access it as in the Doraemon game.

So... whenever those handhelds are supported, that may be something to look into.
I've dumped the ROM from TMNT (and Top Gun); they both use Sharp SM51x MCUs. I'll look into IDing the LCD segments.

The '511 in TMNT has a "melody ROM", so it's possible the power glitch just started it playing.