Can't use my Fairbuds, no sound and disconnect quickly

Hello,
I have a Faibuds XL for few months and I have a problem I can’t solve alone now.
First of all, I did the same tests with my friend’s phone and same result. Secondly this is the second time it happen, Don’t now how I fixed it, it worked one time for few hours and then comeback to the problem.
I can start the headset, I see the white light flashing but no entrance sound.
When I click on the button to change the ambiance mode, no sound.
Then I can connect to my Fairphone 3+ but when I play music, there’s no sound.
And after few seconds it disconnect from the bluetooth.
It did’nt fall, I’m pretty sure it’s not damaged.
I tried to do the reset factory with 5 seconds to the right on the joystick. The headset is up to date.
Can you help me on this please?

Have similar problem with my fairbuds xl v90, but found that headphones plays when connected by usb cable to phone or when is charged with charger. Connection is always via bluetooth, but cable is need for charging. It’s not battery issue ( bought new one), but something has something with the right speaker inner. Have another headphones and try to swap the left speaker and its ok.
Easy pricy solution is to buy new right speaker…
Or wait for might be clever solution in future.
Sounds me problem has connected with firmware…