My LED indicator on phone is blinking rapidly and it doesn't charge.

The phone seems to be charging but it doesn't charge, and the LED indicator is blinking rapidly. Sometimes it charges but at a very slow rate. It also needs to be in a certain position to charge. I also repaired this phone before and changed the charging port. Still, the problem insists. I also bought a new charger but it also doesn't work. I tried cleaning the charging port and nothing changes.