My 2d worth on the brake fluid change query:
My Jazz had its 3 year service last July. That might have included a scheduled brake fluid change. The
relevant box on the Service Check Sheet is ticked. But I can't be absolutely certain about that item.
The electric brake [simulator] [modulator] [servo] [whatever the Dealership likes to call it] failure occurred on 26 March. 7 months and about 3,400 miles had elapsed since the presumed brake fluid change.
If brake failure takes place shortly after a brake fluid change, that could be mere coincidence. I wouldn't jump to the conclusion that there is some kind of causation between the two. It could just as easily have been triggered by a deep pothole that gave the faulty part a sudden shock. Mere speculation, obviously. What most of these sudden brake failures have in common is that they took place on engine start-up, while stationary, not while driving the Jazz.
I pressed the brake pedal while pushing the Start button. Gear selector in P and parking brake on. There followed a series of warning bleeps and symbols appearing on the dash display. I suspect that with my foot on the brake pedal, the corroded sensor inside the brake module had started to give the ECU some pressure readings that were abnormal and/or outside the permitted range, so the ECU shut it down and tried to stop the parking brake being released.
Whatever the actual failure mechanism, the Jazz had become undriveable. Attempting to drive it would be very risky. It needed to be recovered and taken to the dealership ASAP. In fact I had to wait 9 days for a workshop appointment. In total I was without the Jazz for 21 days. Not a good experience.