Thread revival - just fixed my non-operating hazard warning switch.
Fished out the nav screen, separated the three layers of back cover / PCB / fascia and removed the actual hazards button. This sits on top of two little plastic dowels, which run through holes in the fascia and sit on two little micro-switches on the PCB. There is no button ‘click’ per se, it’s just one push for ‘on’ and one further push for ‘off’. Mine was sticking and not activating properly.
Problem solved by removing the dowels, manually activating the micro switches several times with a very narrow screwdriver and then re-assembling everything. Must have just been lack of use, as the hazards work fine now!!