Not charging

Hiya, iv had a problem with my Iphone 3g, well few weeks back My phone got down to 1% and completely died, it turned on with a black screen,no apple sign and then It cut out, well 3days back i got a new battery that cost me £25 and fitted in, on that day my battery went down quick so i charged it up and my charger didnt seem to working, it had a zigzag line for about 4/5minutes and then went to a bold power sign to I tunes , Iv researched what to do,and none of them seem to work (like sinc it up,,Press and hold the power and homebutton) it cuts out within 3seconds,) I Dont know what to do weither i buy a new charger but what if that dont work? and iv waisted mymoney., its costing me a fortune!

now my Battery is dead,

If anyone could suggest some options please Do, x