Try this solution
Turn off or disable Bluetooth® on nearby devices that previously connected to your product.
Your product remembers the last several connected devices so it can quickly reconnect. If there are previously connected Bluetooth devices nearby, turn off those devices (or turn off Bluetooth in their settings menu), then check if the issue is resolved.
Make sure your earphones are in pairing mode
Press the button of either Melomania 1/1+ Left or Right for 3 seconds. You will then hear the “Waiting to Pair” voice prompt. This means your earbud is now able to pair to a new or existing device. Enter your device's Bluetooth settings and locate Melomania 1/1+ L or R. This should now allow you to pair successfully.
Do you have the same issue with other Bluetooth devices?
Try pairing your earbuds with a different device to determine if the issue is related to the first device or its settings.
Clear the memory of your Melomania earbuds on the device you wish to connect to. Then try connecting again.
For options 1, 2, and 3.
Bluetooth devices typically remember the last several devices they connected to so they can quickly reconnect to them. In case there is an issue with the device memory, remove your Melomania product in the Bluetooth device list, then reconnect. This list is normally found in the device's Bluetooth settings. This can be done by ‘forgetting’ (on iOS) or ‘unpairing’ (Android) your earbuds.
You can then try reconnecting to the device as if it were a new device.