Nokia 6101 multiple errors complex situation, im open to discussions

Going directly to the point i got a nokia 6101 from my mother that doesn't works properly and if someone ask later i want to fix this phone to first get some saved files from it and second use it as a personnal device I can use in my school normally and quietly so before start with the description of all events i highly recommend the reader to look at my first outdated post about this but I will still tell about everything anyways.

1°|First contact|

After be patient for a while I found the correct charger for my phone but here it comes the first obstacle from all the coming ones.

Here's a little bit of context about what you have to know if you didn't completely understood the displayed video. As we can see at the moment I plug the charger output in my phone it doesn't runs correctly because the first screen shows a "Contact Service" message highlited by a purple text, then after oppening it the screen shows random pixels like a way similar to that weird pokemon games error called "Missingno" but at the moment I try to restart the phone the same problem keeps occuring, now anyone should think that this is a battery problem or something else related to the power connections, I'm not saying it is not true but this situation specially happens when my phone is "charging" between quotation marks because in reality it never charges up even a 1% using 2 chargers and after 3 hours meaning that is the most probable theory from others indicating the baterry was completely dead so I thought I had to replace it using a second battery me and my father bought in a local market so going to the point I want you to remind that the second baterry was manually charged with another 9v volts baterry as in some techniques to revive a dead one and we used to insert it to see how it works and this was the result.

2°|New lands|

This may be the most important characteristic of all this situation so be very focused on these 2 videos.

So as both videos show there are 2 posibilities to make this error happen at the moment it starts, well in both cases the phone starts correctly after some seconds when it gives up and completely crashes for the first case, for the second one the change is a little bit more unexpected and terrifying in my opinion dying literally after the logo appears distinguishing this case from the other one with some audio participation making like a 3 louder "toc" or "knock" sounds before fall in silence and then lose control to do uncontrolable clicks again until I press the red button being honestly the symptom where the problem can be located but also the same screen gets covered by a white background like it is in a transition instead of just turn off so if you have an idea about it write it later in the comments section apart from your opinion from this post because this didn't finished yet.

3°|Inspection|

Later at the same day I recorded the videos I decided to think about someone who wrote in my last outdated post saying me to search for rust, dust or humidity in the phone interior so I started disassembling part by part and taking pictures of all the process where i will describe every one of them.

There's an strange black spot under the cover althought I guess it doesn't means a lot because it can come from the battery chamber

The terminals and the phone structure seems to be clean in this point with no suspicious warns

The keypad also seems to be clean in both sides

Since this moment i found something like dust above all that plastic cover where if I'm not wrong the displays connects to the motherboard but there's no too much to cause all those problems

From now there are more detailed things someone may think it is unormal to be there as possible rust on the metal because it looks a little weird like if gold paint fell on the surface but correct me if I'm wrong just to not missunderstand, something even more disturbing is that dirty zone on the buttons and i think that can't normally happen to a phone in good conditions

Now looking at the back i didn't found something interesting to talk about than the rusty board and also there's nothing wrong with the terminals or pads i can notice yet

This was a test to let you analize the phone in a better way because someone could ask me show this class of media so now it is the time for you to start commenting and as I said in the title I'm open to any class of discussion or answer. I will wait you.

4°|Personnal conclusion|

Finnishing with this post i want to express this is a problem with so many combinations but it has important aspects like the weird sounds it makes, the glitched pixels, the fact it crashes after a defined time without including the ocassion I plug the phone and the dirty interior in unique clues that will help us to finally solve it and run this piece of art,
I'm not obligating anyone to join me but i think you and me will be satisfied.

Thanks for reading.