Changing to marcoschwartz's library still does not help: the LCD is still blank. (using the code in post-1; my DSL is down at the moment so I can't try the official code with MQTT connection, and I doubt it would make any difference because I carefully copied everything related to LCD)
A few doubts are:
- I don't see any code choosing which pins are used
- LCD module is powered at 5V. How could it communicate at 3.3V logic?
- I2C communication requires a 4.7K pullup, but there isn't a resistor in the kit.
I have already tried swapping SDA/SCL lines, powering LCD at 3V3, and replacing the jumper wires. None of these helped. In each case, the red LED on the back of LCD lights up, but LCD itself remains blank.
I could test the LCD with a Huzzah Feather, if you tell me how to set the pins.