EP-T21 left earbud unresponsive to touch, blinking green

I received the EP-T21 earbuds yesterday.

They are fully charged.

The right earbud works properly.

The left earbud has a green blinking light, it flashes constantly, whether it is in the charging case or not. It does not respond to touch at all.

I have not been able to reset it, pair it, etc. Nothing works, the light just keeps blinking green.

What can I do?