After a couple of years of the light unit laying in my garage I decided to cut the circuit board out to find out what had died. It seems very overly complicated for just a few LEDs. Each LED has its own voltage control. I've managed to cut it in such a way that there is no damage to the board and the cutout could be very easily be glued back in again.

I think the light unit cost nearly £380, surely with the board being so easy get at someone would be able to offer a replacement or repair the board.

Has anyone successfully repaired their headlight unit?

There are a lot of Surface mount devices (SMDs) on that board, which are a bit of a fiddle to remove and replace without damaging the tracks on the board.

Printed circuit boards are generally reliable, what were the symptoms, complete or partial failure ?  And can you connect it to 12V supply to carry out any voltage measurements ?

A friend looked at it and said it needed to be connected to the car? so I just left it and seems a shame as was as new.  The leds all failed at once. 

In that case, it is likely to be something that is  COMMON to all leds, like something in the supply or return.... do the plugs/sockets all look OK.... any iffy looking soldering.. discoloration due to overheating? 

I guess if they all start failing then some clever person who understands the electronics will work out what the fault is (probably just one component) and start marketing replacement exchange PCBs . Or some altruistic person will put a video on youtube of how to do it and we can then do it ourselves with a soldering iron and a one pound component.

My mum's boiler went wrong. It seemed the PCB had falied , replacement over £100. Recon board loads of adverts about £35 I think it was so those people knew what the fix was. After hours of searching I found a youtube video of someone showing which one single capacitor it was likely to be. I replaced that one capacitor and it fixed it. 

Hopefully if they all these headlamps start failing then someone will kindly spend hours working it out and share it with the general public