I replaced my charging IC but the phone is still not charging.Why?

Guys around 1 week ago I connected my iphone to a faulty charging head and immediately my phone went dead,turned out that the phone had a broken charging IC,so after giving it for service they installed a new charging IC ,now although the phone powered up and is working just fine but the service guy says that it isn't charging and despite a lot of effort he couldn't get it to charge so basically that phone is good as dead to me now unless someone knows how to fix that.Anyone here knows how to fix this problem so I can convey it to my service guy?