On some units the wires from the LED controller on the back of the unit to the LED bulbs in the mirrored doors have been installed too tight.
When the doors are opened and closed the wires pull and the pressure can cause them to break at the point where they go through the hinge.
If the wires break and expose wiring from its rubber insulation casing, that exposed wiring can cause the overheating of the surrounding area by the hinge and cabinet while the light is on. The lights may also stop working.
What to do...
Stop using the lights on the units and call or email Mitre 10 to organise replacement or refund.