...the only hints he gave were that he completely rewrote the software...
I think we've exhausted the Arduino nature of this topic, so this forum is probably not the best place to proceed.
Also, coding badly, data sheet for attiny20
says its ISP. Does that dramatically change things?
Connect how? to have a good seat for programming it or just for probing like with a multimeter??
Just include series resistors; 220 ohms works well.