That's great! Glad hear you're back in business. When I had a similar problem it was because I re-flashed the nanoKenbak-1 firmware (through a serial port that I had added) without realizing that I needed to change those two bytes from Mark's stock code. It should be noted that since the "New"
Kenbak-1 also uses a DS3231 RTC, the same two lines need to be changed when re-flashing its
firmware. Only the original
Kenbak-1 kit (which didn't even ship with an RTC module originally, and then was modified to accept a DS1307 RTC module) works with the unmodified firmware.