8x8 Matrix - Hall sensor error

[johnwasser]

@guz_code

I checked the voltage on pin 53, 39, 6 (all the corners, not sure if that was significant) They all read 4.77V without a magnet and 20mV (basically zero?) with a magnet.

Sounds perfect. I can't figure out why the LED for Pin 53 is not ON when the magnet is present (input LOW) and OFF when the magnet is not present (input HIGH).

To enable the internal pullup, use pinMode(pin, INPUT_PULLUP); instead of pinMode(pin, INPUT); The 10k pull-ups you have are fine and you can use both if you like.