On the “Restore from Backup” dialog, it isn’t obvious from the subtle change in brightness of the “Start Restore” button whether or not a PBB file has been selected. And even after a file has been selected, there’s no way to tell which one it was before pressing the “nuke my Pixelblaze and replace it with ???” button.
Adding the name of the selected PBB file to the “Restore from backup” dialog would give a better visual indication that a file has been selected, and a confirmation of which file is going to be uploaded.