''This is a belated answer so hopefully it can be of use to folks who search for and find this question.''
Whenever there are charging issues with a phone, these are the steps to take:
* If the phone boots, use a battery utility, such as [http://www.coconut-flavour.com/coconutbattery/|coconutBattery] (for Mac) or [http://www.3u.com/|3uTools] (for Windows). It will tell you what the health of the battery is. Anything less than 70% of design capacity will require replacement.
* If you have access to a [https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=USB+Ammeter|USB Ammeter], you could use that to determine if the phone is really drawing current when it says it's charging.
* Insure you are using high quality Apple original or MFi certified cables and chargers. Cheap chargers can damage the charge circuit on the logic board.
* Replacing the battery is always a valuable option
If a new or known-good battery doesn't solve the problem, then you likely have a logic board issue.