When replacing parts does not provide a solution or resuscitate your device, the only explanation is a failure of the Main Board or the Logic Board.
When a device suffers damage, the obvious problem(s) appear to be a component, for example a screen or a charging port. These component failures are readily and immediately experienced by the user to be the proximate problem. Replacing the damaged or non-functional component would seem to be the obvious solution. Thus, a user comes to The TechKnow Space to have this problem remediated/repaired. Typically the doctor (our seasoned technicians) have no problem doing this.
Sometimes however, replacing/repairing components turns out to be an exercise in futility. Further diagnostics establishes the problem to be resident in the Main Logic Board. The replacement of these logic boards is prohibitive and best left alone. It’s time to move forward to a new device.
Bear in mind that these mainboard failures are a result of the initial damage to the device that prompted a visit to the repair shop even though it is not intuitively obvious.
Read a more detailed mainboard failure explanation here.