Weird battery behavior?

Question

Rechargeable batteries

Hello.
I have an old galaxy 2, I bought a couple of 1650 mAh, 3.7v batteries from China. At first they worked fine, but then one after another quickly "died".
How it looks:
- we discharge the battery in the phone
- we put it on charge - the phone shows "charging", but the progress is always near zero. If you disconnect from charging - the phone turns off.
- we take out the battery - the voltage on it is 3.3v
- the battery lies for a week - the voltage does not change
- we connect a computer fan to it and hold it for an hour - we
measure the voltage - 4v.
- we insert into the phone - the charge level is 87%
Question - HOW? Why did the battery charge, but the voltage did not change until it gave a load. Where was it? What is the physics of the process? It should be the other way around