JBL Tune 500BT Headphones Not Pairing with Phone: Bluetooth Connectivity Issues

I warmly welcome!
Due to the fact that I did not find a similar problem, I was forced to present it myself. Namely, I bought the jbl tune 500bt bluetooth headphones about two months ago and so far they were working, they sounded as they should. Until yesterday evening. I went home, the headphones were on all the way, I turned them off of course, beautifully put away in a safe place. After about 30 minutes, I turned them on again and at first the phone wouldn't pair with them, so I turned them off and on, still the same. I disconnected the pair on the phone but the phone stopped searching for them at all, as if they were not turned on. Interestingly, they are charged, a characteristic sound is heard when turned on, the LED lights up in white. When I want to turn them off, I have to hold the button for about 2 seconds, but about 7, because they do not want to turn off and the sound that would indicate their turning off is simply not there. I tried to connect them to another phone, but none is finding them. Can something be done about it? Do you already go to the store and advertise? I would like to add that it is not possible to dig inside, I do not know electronics at all

As the advice of a colleague above will not work, give the guarantees immediately, just do not start anything there because he immediately states that it is your fault.

Nothing helped, the phone still does not find the headphones, although the LED is flashing blue, i.e. waiting for a bluetooth connection. Well, thanks for the advice, I will give the equipment back for warranty