iPhone crashed, stuck on cont reboot loop, now can't even restore

My iPhone 6 randomly crashed the other day and got stuck in a reboot loop where the apple symbol would come on for a few seconds then go blank black screen for a few, then back to apple logo etc. I tried powering down, resetting with home + power button, etc, and nothing would work.

Plugged it into iTunes, it asked me to update it -> after running through the process it said it was unable to update, it must be restored. After trying to restore, the same thing happened -> an error message saying it was unable to restore it.

Ive update my OS, updated iTunes, tried restarting everything, etc -> nothing has worked.

Now when i plug it in to charge it shows a black screen with the symbol to plug it into iTunes.

Finally i took it into a repair shop -> my wife ended up picking it up so i didnt get the full explanation but she said they reported that they couldnt fix it because it was a software problem and i needed to take it into apple.

Help!