Modifying the code to work with the 16MHz crystal failed, but I believe this is because of the physical setup - the crystal is on a breadboard pretty far away from the chip, and I’m talking maybe 7" or so of wire. Nothing lights up when I run the code. I’ll try that again with the crystal on the PCB when I make the proper board for it.
I then tried modifying the code to follow the commands somers’ code goes through and unplugged the crystal, and success! The LED flashes nicely.
Thanks so much for all of your help!
Now to figure out how to code the thing… 