It’s normally the impeller in the sensor ,isolate the cold and open taps put a towel in case of spill’s around the pcb area , remove circling and it may come out in one piece,or have one ready to fit.
Hi its just the voltage is wrong regardless of whether the sensor is connected to the aqua...
i have seen plenty of previous no hot water ch working fine as mine.
No demand or running lights come on when tap turned on. Also water diverted works as pre heat water works.
But on mine the aqua sensor lead black and red gives 4.8 v but black and green also gives 4.8v regardless of wether tap...