I have a heatermeter v4.3.4 that was pre-soldered and works fine. I loaded the latest stable firmware on a raspberry pi 3 B+ that has 2017 screen printed on it. When I try to boot it will only display the rainbow test screen with a yellow lightning bolt. I also tried the snapshot image and that didn't work either. I tried moving the sd card to another identical 2017 rpi 3B+ with the same result. I then tried the SD card in a 2015 rpi 3 B and it worked fine. Does anyone have any suggestions to get the 2017 rpi 3 B+ working or maybe a later date of the rpi 3 B+ would work?
