iPhone dead

[[TW]Fox]

Hi all,

I have an iPhone 5S which I use in the car for Spotify (don't ask). The other day the music stopped and I assumed it had lost internet connection or something but when I got home and checked the handset it was powered off despite having been plugged in.

I am since unable to get it to power on - I've charged it overnight, I've pressed on and home for 10-20 seconds, nothing will bring it back.

Any ideas?

 

[[TW]Fox]

Plugged it into a MacBook and it detected an iPhone in recovery mode. It downloaded the latest software and then attempted to update it - screen came on with apple logo. But then it fails with an unknown error.