since its not doing anything I would say try to factory reset with tooth pick and insert into audio video hole and keep holding while powering up your box and see if anything comes up on screen. if still not then I would contact buzz team and let them take care from there.
turn you tv ON, disconnect power from the box, wait 30 seconds, reconnect power and see what happens? do you see blue light? do you see anything on the screen?
you can store anywhere in your box then go to m3u option and select location where you stored your file.
I usually transfer m3u from my pc to download folder in my boxes via TeamViewer. then I launch buzz app on my box, go to m3u option and select download folder and thats it.