Cannot connect my Logitech M720 triathlon mouse which was previously connected.

I've had the mouse connected for several years, but lost the connection a few days ago, and haven't been able to reconnect. The Bluetooth is discoverable, I've replaced the batteries in the mouse, but after it's completed the "Search for nearby devices," and lists the mouse, it just spins and spins after I enter "Connect."

I am using MacBook Pro 13" 2016 running macOS High Sierra.

Thanks