iPhone not working at ALL.

I've purchased an iPhone 5c from a guy at school, I asked him to turn it on but it didn't turn on. He told me it was dead, but he had already reset it & was ready for someone else to use it. I previously owned an iPhone 3GS (Which got STOLEN) So of course I was excited about purchasing a BETTER phone. Once I got home and plugged it up, it wouldn't turn on. It doesn't matter if the phone is completely dead or not, the Apple logo should STILL pop up and show the red battery sign. I left it to charge overnight & woke up the next morning....the phone STILL wasn't working. I've tried everything in my power to get this thing to work. I've tried DFU Mode, Hard Reset, Recovery Mode, charging it, cleaning the lent out of the charging port, tried a different charger, etc. It's STILL not working. I'm assuming it's a hardware problem. I've also checked for water damage and there's NONE. PLEASE HELP!!!!!