Please help, I installed a carel mastercella controller to a cold room about a year ago. When I went to it I could not access the parameter menu. The light switch button is not responding or is the on/off button. None of the buttons seem to be responding. The parameters seem to be gone back to default values. Would it be a case that the keypad is locked or is this function available on this controller. If so could somebody tell me how to unlock the keypad? Or is it a case that the keypad is faulty? I would appreciate any advise, I have never seen this type fault before.