hi,i dont have this adafruit product ,but i do have there captive touch hat, and it was treat to get working … there is a lot to do in that link and if its not all done and in correct order i think it can cause issues with the display working properly
Making a typo and not noticing you did it will mess you up too. Been there done that.
I’d start over with a clean new Raspbian Image, then run through the tutorial one more time, paying close attention to what you see on screen
And double check your wiring / jumper wire hookup.
Thanks everyone for the hints and tips. The final cause was tracked down to a dry joint on the rst pin
Anyone else experiencing random pixels in future, I would say the unit has not been successfully initialised. The reset operation is key to its operation