Why my smartphone has huge bugs when it is not plugged in?

Hi,

My smartphone has several problems when he is not plugged in.

First time, it was when I used the camera in Vietnamese mountain. It was during the raining season and it was very very humid. The phone suddenly turned off. Since this day, when I use the camera, my phone frequently turns off.

I broke my screen for the second time. It was still there, with this very humid environment. Then, my phone started to have more and more problems.

Now, when my phone is not plugged in, it:

- turn off suddenly,

- does not found the GSM network

- ask several times the PIN code

- turn off again ...etc...

and now, these problems are almost permanent, but, I can use my phone normally without problem when I plug it in external battery or the mains supply.

I thought that could come from my broken screen... but I have changed it yet and my phone is still not working properly.

One more information, the first time I had fixed my phone screen, I did maybe some damages to the battery. The battery was very well stuck. I forgot to use the plastic tool. I use the screwdriver to lift the battery.

Do you have an idea of where this problem come from?

Do I have to change my battery?