The are only a handful of issues I can think of here would either be a bad charge port or that TriStar could be damaged as a result of using poor quality chargers or you might’ve caused board damage during repair or the port might have dirt and debris stuck inside.
TriStar is a USB validator chip that makes sure that whatever accessory you plug in to the lightning port is safe to use and verifies that it’s a certified accessory. This is why you get the message saying, “this accessory may not be supported” message when using some third party accessories. The reason why this system is in place is because certified accessories have surge protection built into them and cheap or fake accessories do not. In simplest of terms, TriStar is like a bouncer at a night club and checks the ID of everyone that wants to come in. When a fake accessory is plugged in, it essentially uses a fake ID. when TriStar gets damaged, the most common symptom I see in my shop is the device won’t charge when it dies completely no matter how long you let it charge. There are tools readily available to test TriStar and the charge port and I’ll link them below. If you don’t want to invest in the tools, some repair shops might already have them so call around and ask!
USB ammeter: https://www.amazon.com/DROK-Multimeter-Multifunctional-Electrical-Capacity/dp/B00J3JSEG6/ref=sr_1_5?crid=39GNN6VO0K5HD&dchild=1&keywords=usb+ammeter&qid=1616686718&sprefix=usb+am%2Caps%2C193&sr=8-5
This tool will tell you how much current (amps) the device draws which will be represented by the blue numbers and it will tell you if the port is bad. If it reads 0.00 amps while the device is powered on or even off, then it’s most likely related to the port. If it cycles between 0.01 and 0.00 while the device is dead, then it’s most likely TriStar. The second tool called the TriStar tester can help confirm whether or not that’s the issue.
TriStar tester: https://www.mobiledefenders.com/tristar-tester.html
If the port has dirt or debris stuck in it, you can clean it out with some fine tipped tweezers. Just be careful and don’t be too aggressive.