Airpods won't connect to iPhone or MacBook Air

Hello,

My AirPods (which I'm fairly sure are first generation) are no longer syncing with either my iPhone or MacBook Air. At first, the AirPods were visible under bluetooth devices, but disconnected only seconds after I selected them. Then, in an effort to disconnect and reconnect AirPods from my bluetooth devices, they are no longer visible, and I can't seem to connect them to bluetooth. I've tried restarting my phone, computer and AirPods (by holding down the button for 15 seconds), each with no success.