iPod classic not recognized on iTunes and stuck on do not disconnect

okay so i have this iPod classic and every time i plug it into my mac it says "do not disconnect" and it doesn't even pop up in my itunes

and then i toggled the hold switch and then pressed the center select button and menu and it said "connect to iTunes" and exactly right after that it turns off completely and this has been going on for hours someone help me ! i just want to be able to use it again. just wondering if there a program i can download to get it to work again someone please help