My A1 hotbed temp started fluctuating down then would rise, then drop sometimes to zero. this would happen after printing 5 to 10 minutes after starting a print. I struggled to determine why. Using a Infared thermometer, I found that the temp actually was going up at times on the hotbed…Yet on the display screen it showed it was going down. Then finally the screen said: heatbed temp malfunction 0300-0100-007. What I found was that code meant there was an open connection caused by the build plate out of position. After removing the plate I noticed 2 very tiny metal contacts that are at the rear that have to contact the build plate. After making sure that the build plate makes contact with those 2 tiny contacts Everything returned to normal.