If the indicator lights of the two earphones are flashing quickly, it indicates that the Left and Right earphones are not actively paired.
Step 1
Turn off your mobile's Bluetooth.
Step 2
Put the two earphones back into the charging case and close the lid.
Step 3
Put the two earbuds on the table and wait 15 seconds for them to be paired automatically. The indicator light of the lead earbud flashes quickly, and the other earbud flashes slowly.