On charging issues, there are three things that coud be causing the fault:
- A bad battery. A new battery doesn't always mean a good battery. There are plenty of low quality batteries out there.
- A defective charge port (which you changed). Again, a replacement charge port doesn't always mean a good part. Small parts also have high failure rates.
- A charging circuit problem, specifically U2/Tristar.
So have you changed the battery with a known-good battery? Or can you test your battery in another, working, device? The same applies to the charge port. If data retention is not an issue, you could always try to reset your device or put it in recovery mode and re-install the firmware.
Barring that, you probably have a defective charge circuit. Does iTunes recognize your device when it is plugged in with an original Lightning cable?
That requires a micro-soldering repair and is not really a DIY fix.