Puck2.js Master/Slave: probem (red LED) when establishing the connection

Is it possible that you're still connected to the slave device with your PC?

Espruino BLE devices can only have one device connected to them at a time, so if you're connected with your PC, the 'master' device won't be able to connect.

Also, if you stay connected with the 'master' you could change the code to:

    }).catch(function(e) {
      digitalPulse(LED1, 1, 500); // light red if we had a problem
      console.log("Error",e);
      busy = false;
    });

And you might be able to see what error it is complaining about