Since decathlon love to change name from time to time here is a picture of the item.
l While it seems to be tightly sealed (thanks ipx4), it is possible, applying some brute force and with the aid of a screwdriver to separate the rubber shielinding from the actual lighting element.
Wait, but why am I doing this?
Basically the light stopped working, the button does not activate the light anymore, but I guess it is not a button problem because while charging the charging led has a weird behavior, it is both green and red and is it possible to use the light, so I may conclude that the battery is the culprit here.
The light itself does not seems special, it’s powered via 3.6V LIR2477 button shaped rechargable battery, connected to the main board with power the light (2 mode white light + recharding red led), does it make sense to have 5 pin going to the light?
Toss away or substitute? Well, the price point for a battery replacement is ~10€, which then needs to be soldered (from the board it seems almost SMD so moderate screw up probability). I guess I’ll pass, moreover the light quality is not so great for out-of-the-city rides, BUT it could be interesting to scrap the light element to use it in some electrical project (raspi et simila).