All, I had a working LED matrix panel that uses one of those little MAX7219 boards that has the chip, capacitors and resistor plus the headers. Really simple, running off an arduino nano, with a fully working sketch, no issues.
So yesterday I plugged it in again (it's part of a flight sim cockpit) and it wouldn't work, with either nothing being lit or all being lit. Nothing at all had physically changed. I have a couple more of the MAX7219 modules, so I tried those, with the same result.
So to troubleshoot, I have got one of the example sketches, and simply connected an 8 x 8 LED matrix module direct to the board, and tried that. Nothing at all, and all three MAX7219 modules appear bricked! it's virtually impossible to get the wiring wrong, and when you connect them all the LED's come on, and stay on except for dimming after 30 seconds or so. Nothing else happens,even if I press the reset button on the Nano, and the only thing that has any effect is pulling the USB plug out of the Nano, waiting a few seconds then plugging back in, and all that does is light all the LED brightly again.
I'm bemused, as I really have changed nothing at all, and can't get anything working even with simple stuff. Are MAX7219 chips so sensitive? Even so, I don't remember any loose connections, and even if there was it would only have been to one of the LED's - surely that shouldn't brick them?
I'm looking for any advice or troubleshooting tips that I can get, as I'm assuming that it would be the MAX7219 chip itself that would fail and the capacitors and resistors should be OK? I didn't notice anything getting hot, or electrical smells, power was exclusively through USB and the LED's work fine with no short circuits ( I checked it out)
Any advice or experience you can share gratefully received