Why Does My iPod Turn On and Off Repeatedly?

I recently bought a pink iPod Nano 2015 and I charged it completely before anything, then synced my songs on iTunes with my MacBook Air 2015. Once I pressed "eject", it started going haywire and turned on and off repeatedly. I then decided to return it and got a blue one. I did the exact same thing and it too started turning on and off continuously. I can't make it turn on, reconnect it to iTunes to put it into recovery mode or update it, and can't turn it off. How do I fix this?