-- get a digital hygro, test and calibrate it.
Also, taking your beads out and leaving the door open is not a good idea. Make sure your beads are doing what you want -- put them in a ziplock with the new, tested, calibrated hygro and see what RH they are at.
Also I can't tell you whether you should leave the cooler powered off, but you should make sure that the drain plug is sealed up. You want to make sure that your unit is sealed.