I don't know why you would be getting that error. As far as I remember the mc70 didn't have a battery door switch. It just closes and has the little wings that clamp the door into position. Here is the manual for your model http://peachinfo.net/downloads/mc70UserGuide.pdf
Page 20 shows the door and operation of the door is on 24. Try using a different battery.
Try doing a cold boot of the device after changing the battery. Maybe there is a third party device driver for a aftermarket door installed. It might not be reading the device correctly.