Hello mannes2111,
Thanks for participating in the Apple Support Communities!
Since you recently received a new Powerbeats Pro charging case, check out the steps below to see if they may help with clearing up what you're experiencing. Additional information can be found towards the end of this resource: How to send your Powerbeats Pro charging case to Apple after receiving a replacement in the United States and Canada
Set up your replacement Powerbeats Pro earbuds
1. Put both Powerbeats Pro earbuds in your charging case. Keep the lid open.
2. Check the LED status light on the front edge of the case. It should flash red.
3. Press and hold the system button on the inside of the case for 5 seconds. The status light should flash white. If it still flashes red, connect the case to power, close the lid, and wait 20 minutes.
4. Pair your Powerbeats Pro with your device.
Pair with iPhone
1. With your earbuds still inside and the case still open, hold the Powerbeats Pro next to your unlocked iPhone. A setup animation appears on your iPhone.
2. Follow the onscreen instructions.
If you're unable to complete the set up with those steps, Contact Apple Support to check into this in more detail to explore replacement options.
Have a great day!