Bought the RGB matrix backpack and USB FTDI TTL-232 3.3 cable from Adafruit last week. I had been using the RGB matrix 16×32 from Adafruit with my Propeller micro-controller and it is working fine with my 5vdc 10A p/s for the 16×32 rgb matrix display.
Im an EE with 35 years experience soldering and when I plugged the backpack in to the matrix and wired to the matrix 5v terminals correctly I saw nothing on the display. I checked to make sure I had 5vdc on the matrix terminals and that was good. Nothing was overheating and retouched all the solder connections a couple of times so thats good. I even downloaded all the matrix libraries and the demo code and was able to sucessfully download the arduino packman demo code to the backpack with the new cable I bought also. I then disconnected everything and made sure the display is still working by connecting it up to my propeller microcontroller and program and everything was working on the display.
This leads me to believe I have a bad board, soldering? or other issue.
Glad to hear that you have found out the problem. However, I am facing the very same problem here. But, what you have said here is not working for me. Can you suggest any possible workarounds for this one?