Issue running Max7219 controller - All LEDs constantly lit
Hi, I'm having a weird issue with my max7219.
I have 8 7-segment displays hooked up to it, wired up on a stripboard. When I power I power up the arduino, all my LEDs get lit, no matter what I set the digits to. Some quick research online has shown that this is probably the test mode for the max7219.
I've tried to test my connections, studied the diagrams, stared at all my wires, trying to find something I did wrong, but I can't figure it out. Does anyone know what might cause the max7219 to go into test mode?
Note: Lots of people online with similar issue got the polarity of the displays wrong, but I have already checked that.