In a development of 'is my IQ-X fucked'? it turns out that the 'problem' was me, total user error fail.
Had routed my rear light via the mudguards (in both wheels as the front is on a front rack) and I'd been running much too close clearances and not secured the coaxial well, got rubbed over a year and water getting in was the last straw. I discovered when I realised the light was fine without the rear attached, then excluded the rear wiring with another light and discovered everything was working, ergo my wiring was fucked.
Thanks to @Klar for mentioning that I'd introduced doubts about the IQ-X plus water. Turns out I was totally wrong. It's a really good light too.
From experience it's always worth checking your connections at the rear light if you ever have a problem with both lights, it's easy to accidentally get a dead short with cheap rear lights and their connectors coming loose.
In a development of 'is my IQ-X fucked'? it turns out that the 'problem' was me, total user error fail.
Had routed my rear light via the mudguards (in both wheels as the front is on a front rack) and I'd been running much too close clearances and not secured the coaxial well, got rubbed over a year and water getting in was the last straw. I discovered when I realised the light was fine without the rear attached, then excluded the rear wiring with another light and discovered everything was working, ergo my wiring was fucked.
Thanks to @Klar for mentioning that I'd introduced doubts about the IQ-X plus water. Turns out I was totally wrong. It's a really good light too.