iPhone 6s Plus -- Unresponsive

This occurred 2 days ago, i was casually using my phone when the screen turned red & then went black completely. It wouldn't turn on, when charged, logo both battery & apple logo would not appear. When connected to ITunes, my computer doesn't recognize it, but iTunes does. I tried to update it but because mid-update i had to confirm the update on my phone, which wont turn on..it won't fully update.

Also, i need to back up my phone..and I would hate to restore it if it won't fix the issue. My phone is in perfect condition, no water damage or screen damage. Would anyone have an idea of what it is? Ive tried every resetting method there is to possibly try. Is it a system failure?