How do I return my s6 Edge to normal from Downloading screen?

I got my new Samsung Galaxy S6 Edge yesterday and wanted to block the annoying Samsung sound on turning on. Followed some instructions on YouTube without realising fully what I was doing (stupid) and now have the phone with a blue screen saying Downloading and with a downward facing arrow - but having listened further on the YouTube video, am now alarmed that I may already have invalidated my warranty. Have tried pressing buttons in various combinations - is there a way back?

Try the Hard reset (Volume Up + Home button + Power button, until you see Samsung logo). If it is not working then root your phone first and then download official s6 edge rom and install it.