Locating serial number WH-H900N?

[GlynG28]

Odd question but where exactly is the serial number located on a pair of WH-H900N headphones please?

I'm a painter and decorator and around a third of the surface area of my headphones have paint on them that's gradually built up. It's an irrelevant cosmetic thing and not hard to scratch off but I don't know where to look and do so.

I've been enjoying my headphones for a year and a half but they've suddenly stopped charging. The red charging light comes on for 30 seconds or so only and then goes off and they won't turn on now. I figure I'll see how much an out of warranty repair would cost vs buying a new pair.

[Marino.Manolo]

[stefffe]

4 years later I come here with an answer yay

It's located here, right over right ear cup, a little bit hidden so you need to turn the cup outward to see it: