It’s one of those On-One 1-LED lights. It switches on, works well, but doesn’t switch off. WHY???

It’s brokded.

has it ever switched off?

It did until it was left unused for a month. I was off bikes for 5 weeks but the light worked before.

my polaris 5 led commuter light sometimes stays on really dimly if you switch it off, although this is intermitent. I reclon its got some water in it somewhere.

I’ve just found this:

Q: I just got my light and it doesn’t turn off.
A: When your batteries are low, the light locks the switch in its current position. This is a safety feature as we don’t want your light to go completely dark on you, but it’s a backup ñ Change batteries after your low battery light turns on.

Result!