My iPod Classic won't stay connected

Everytime I connect my iPod classic to my Macbook I get the connecting screen then it shows the sync screen (yet nothing does actually sync to my iPod) and then it disconnects. This all happens within seconds making it impossible to restore from itunes. It also doesn't stay in Finder.

In disk mode I can keep it in finder but itunes doesn't recognise it at all like this.

I've tried all the steps on the apple support 5 steps, installed the latest itunes, tried different usb ports, tried a different cable and tried on my friends mac.

Is there a way to restore it via finder in disk mode? Or anything else I haven't tried? It's been like this for 3 weeks 😟

Also, it connects fine with my iphone, so its definitely a ipod fault not a laptop/cable/usb fault...