Anyone know what the blinking red LED indicates?

It's on a tiny circuit board (2" x 1") directly on the rear side of the heated printer bed.

By the activity, I'm guessing it indicates data being read from the SD card....but then that really wouldn't make sense being that it's attached to the rear of the print bed.

It's not a hating indicator, because it blinks more like a hard drive light. A heat on/off indicator would probably come on a while then go off a while and repeat.

so anyone know what this might be?