I was having some issues where the Iotawatt could not write to any of the output log files which was causing the program to halt. I tried several SD cards of many different sizes and also tried one with a FAT16 format based on another user’s forum post (Panic modus red-red-red blinking LEDS - #5 by Simsala).
After a lot of frustration I realized that I had named the SD card “IOTAWATT” when I formatted the card and wondered if this could be the problem. So I changed the name of the SD card and suddenly everything was working properly. I don’t know why but this was preventing the SD.mkdir() function from creating the iotawatt folder where the log files get stored.
Hopefully this will help anyone else running into the same issue.