Currently, closing the app by clicking the "X" in the window does not actually close the app but places it into the background processes and into your system tray in the bottom right of Windows.
In order restore the window you will either need to go to the bottom right of your Windows Task Bar and find the BEACN App icon there. (It might be hidden with the other hidden system tray icons under the "^" icon.) You can then right click and restore window or double click on the icon to bring the window back.
Run the BEACN shortcut on your desktop to restore the window.