Carl1975

Hi all, I'd really appreciate some info if possible regarding an LED headlight & module replacement. Car is a 2016 A3 1.6 TDI S Line with full LED headlights. One had a crack in it, eventually getting full of condensation and stopped working (day running lights still worked, nothing else did and it flagged up on the dash as failed). After Audi wanted £1,077 just for the headlight with no replacement modules/ECUs or fitting, I sourced a second hand one. The headlight itself had two modules/ECUs on it, one at the back and one on the bottom. There is also a smaller unit on the back, which appears to be some sort of switch/circuit board. When swapping the modules/ECUs across from the damaged headlight to the replacement, I found the bottom ECU to be very water damaged, so I got a brand new one from Audi (£170). I have put it all back together (so replacement headlight with new bottom ECU) and the headlight still does not work. After swapping the various contollers/ECUs between headlights (the replacement and the other headlight that had no issues), I have narrowed it down to the new module/ECU not working in either headlight. Using the current ECU from the non-damaged headlight, I can get either headlight working. So, does anyone know if I need to get the new ECU 'registered' and set to the car? Can anyone think of any other reason why the new ECU appears to not work? It's the same part number as the original. Thanks in advance