Battery died and the phone no longer charges

Hi

Background

I opened my phone for a quick look after I had dropped it. cable 2 came out and during my attempts to clip it back in it sort of half-broke the clip.

Problem

when I connect the phone to the PC or to the wall connector it does not charge. When I hold the on button after 3 secs it comes up with the battery sign but underneath it has a plug sign pointing to an electricity sign, which I assume means I need to charge the battery because it is dead.

Not sure where to go from here.

Any advice.