Symptom
User interface has no display but Quantum is warm / hot

Check
There is power to the peak circuit, the peak switch is in the on position. if not then switch on.

Check
The peak mains supply is present at the Quantum  mains input terminal block, terminals 3 and 4 (counting from the left) 3 being L and 4 being N (this is fed from the mains filter board, located behind the CC)

If no supply is present at the CC and there is power to the mains filter, then replace the mains filter board.

Check
Connection between the UI and CC is in place at both ends and undamaged. if not then terminate or change damaged part.

Check
That 12VDC is present on the lead from the CC to the UI, whereas red is +ve and black is –ve.

Swap over UI and see if fault clears, if so the fault is with the UI, If not put the original part back.

Swap over CC and see if fault clears, if so the fault is with the CC, if not put the original part back

Check
Connection between the UI and CC is in place at both ends and undamaged. if not then terminate or changed damaged part.

Check
That 12VDC is present on the lead from the CC to the UI, whereas red is +ve and black is –ve.

If the anwer is no then, swap over UI and see if fault clears, if so the fault is with the UI, If not put the original part back.

If the answer is no then, swap over CC and see if fault clears, if so the fault is with the CC, if not put the original part back.