My (almost unused) Sena 10U in a Schuberth C3 Pr has stopped working and (along with everyone else) the support from Sena is non existent.
They suggested that the batteries have failed and it was possibly due to being charged at 2 amps.
I don't remember seeing any mention in the manual of a 2A charge current causing battery failure. They then sent over a technical document showing that the preferred charge rate was only 0.5 or 1 amp and 1.5 was the upper limit for safe charging.
Bearing in mind this was not in the manual and almost all home charger sockets and car chargers output 2 amps, as required for iPads %& most mobile phones, this is more tan an oversight, it's bad design and lack of communication to customers.
They don't offer a repair service and I won't be buying anything else from such a useless company who don't value their customers.
If possible I'd like to get a pair of new replacement batteries LiOn polymer batteries (marked as XK 611343 1060620 300mAh 3.7v 1.11Wh.
I'm happy to fit these myself to see if I can get the unit working again.