My iPod 4th Gens time resets to Jan 1st 2000 and doesn't charge.

I have a modded iPod Classic 4th Gen with an iFlash mini sd card adapter thing. When i charge my iPod, sometimes it freezes on the charge thing and the time resets to Jan 1st 2000. And also the battery icon never fills up its always empty. What can I do to fix it. Thanks!