My iPhone 4S has stopped working?

Hi. My iPhone 4S stopped working last week and hasn't fixed itself yet. The symptoms of the problem are as follows:

1.it's mainly unresponsive. No apps work, they crash upon opening them
2. There's no active internet connection (3G, E, GPRS or Wi-Fi)
3. When i try to enter my password to disable 'find my iphone' it "times out" so I'm unable to do that
4.it doesn't transmit or receive signal from internet/ GSM

Things I've tried to make it work:

1. Restore, reset, hard reset
2. Sign in and out of apple ID/ icloud etc
3. Factory reset
4.re-seating the sim card

Is there anything else I can do to fix it? Plus, is it a software or hardware problem?

Specs:
iPhone 4S 16GB
GSM
Locked on O2

It has no water damage, it's never been dropped and has genuinely been taken care of properly.

Thanks for any help.

Added (1). Edit: when i try to restore it via itunes i have to turn off 'find my iphone' but it doesn't let me due to it 'timing out' (see point no.2 on the symptoms list)

Does it work when plugged into the charger? Could be a dead battery if it works when plugged in. Could be a defective charger not charging the battery. I'd take it to one of your provider's stores and have them check it out.

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