I think you should open the front header, some screw around toward bottom front and some crews at to top that is. The problem I got 2 weeks ago, was too hot and message error turn off the printer. When I open the front heat cover check all connection and foundout the Ribbon connect between 2 heater boards controller was'nt insert all the way down (look like the assemply at manufacture), after insert we leave the heater open you can plug power back in and test, and lucky it work fine.
Make sure unplug power before open the heater cover, check all connection first before check other parts. Hope this help.
Kevin N.