Hi iiidefconiii,
Thanks for the reply!
I actually use /dev/ttyACM0 (My mistake, AMA0 was just my latest test, but didn't work either, just like USB0). I'm pretty sure this is also correct since only with ACM0 I get the flashing in red, green, blue when starting hyperiond. (I also used ACM0 in my formerly working boblight setup).
I also tried hyperion-remote -c red while running hyperiond, but again no effect (though hyperiond logs it).
As for the color order: According to my sketch, RGB should be correct. Even if not, this should then result in wrong colors, but at the moment, I get no colors at all...
The reason why I do not get rid of the Arduino is that I integrated the arduino (as well as the LEDs) within the casing of my TV. Only the USB cable and the power connector are accessible at the moment. So I would rather keep it...