iPod Classic is unresponsive and slow

Salutations,

I got an iPod classic 7th generation from eBay brand new a few days ago. It was a little laggy and the click wheel was occasionally unresponsive but not enough for it to be a true problem. Now I was listening to music and suddenly it froze. I searched for ways to fix it on google. I tried the hold switch on and off and then the menu and select button thing a copious amount of times. I then tried to put it into diagnostic mode but to no prevail. It still shows the screen and the song I was playing. None of the buttons are responsive and the display after a few hours has yet to dim or turn off. I tried connecting it to iTunes but it doesn't recognize it. I am running the most current version of El Capitan and most recent iTunes. The iPod is a black iPod classic 7th gen 160 gigabyte model. Please help me if you can Ive been looking everywhere!!!