Iphone 4 stuck on black screen?

My iphone 4 is stuck on a plain black screen (still gives off some light.) I've tried doing that hold home and start for 15 seconds thing but thatdidn't work. Itunes can't detect it either.
It was also frozen on snapchat before it went black.
Its plugged into a wall charger right now but i really don't want to take it in anywhere because the closest apple store is hours away.

Added (1). I already tried hard reset

Simpsons Tapped Out Donut Hack?

I have an iPhone 4s, which I have recently jailbroken. It has Cydia, Mobile Terminator, and iFile (of course I can download more). I would like to know how to get unlimited donuts with Cydia WITHOUT TAKING any surveys. I'd like to know if the hack still works currently.

P.s., It would help if you know of any good hacking websites that update new hacking tutorials for the relevant game.

Could my iPhone 5s be water damaged? Or am I just an idiot?

It was pouring while I was in the car, and when I got out, I ran to the door of my house like anyone would. I then realized I left my iPhone in the car. I ran outside again to get my phone, then I saw it on the ground in the rain. I quickly picked it up and ran inside to dry it.

The phone seems to still work fine. Nothing seems to be wrong with it. It had a case on it and screen protectors on the front and back of the phone. I have it on the charger right now, and it's charging fine. There's nothing that doesn't seem to be working, but could it still be water damaged? I've always taken good care of it- no scratches, no marks. I need to know, because I plan on selling it in the future.

Should I get the 4S or a 5S/C?

My dad told me that he'll be getting me and my brother iPhone's during the summer holidays. I'm starting college soon, and as sixth form life requires responsibility I thought the more mature decision was to buy a used iPhone 4S and sell it on later when surplus to requirements.

Should I get the 4S nor or wait until my dad actually get the 5S/C. What is better in your opinion, a 5S or 5C?