Problem with bluetooth transmitter

Hello! I’ve bought from Amazon in 2019 the BR-O2 2-in-1 Wireless Transmitter and Receiver. I use this device with my TV to connect Bluetooth earphones. Until a few days ago it worked pretty well, but now i can’t no more connect my earphones or pair a new one. In the manual I haven’t read about a reset future. There is a way to do a complete reset to get aukey still working? I’ve tried to contact amazon seller, but the workaround they suggested to me doesn’t work (hold for 8 seconds the multifunction button).