Sennheiser MOMENTUM True Wireless 3 Noise-Canceling In-Ear Headphones (Graphite) - Manual (Page 18)

Using the earbuds
18 | MOMENTUM True Wireless 3
If the LED does not light up:
• Clean the contacts on the earbuds and in the charging case
(> 37).
• Make sure that the charging case rests on the wireless
charging station (maximum distance 3 mm).
• Wait for at least 10 seconds. With some wireless charging
stations the charging process starts delayed.
• Observe the setup instructions of the wireless charging sta-
tion so that no electromagnetic fields or materials influence
the charging station (see instruction manual of the wireless
charging station).
• Charge the rechargeable batteries of the earbuds and the
charging case (at least 30 minutes) until the LED lights up
again.