You need to check the thermocouple connections on the motherboard.
- Turn off the MakerBot Replicator 2
- Gently turn the machine onto its left side
- Unscrew the hex screws holding the metal mother board cover in place and remove this cover
- Now locate the gold wire inserting into the green block in the bottom right hand corner, labelled "Red" "Yellow" (see picture "Motherboard" attached)
- Unscrew the holding screws with a and remove the 2 ends of the wire.
- Put the red wire of the thermocouple wire into the "Red" terminal (A section) of the green block and the yellow wire into the "Yellow" terminal (A section)
- Tighten the screw and make sure the wires are secure
- Turn the machine back upright and turn the machine on. Try building something.