Chosen Solution
For the start, my battery does not last more than 5-6 hours. And when it drains completely it does not react to the charger anymore and stays totally flat, like the electricity is not even coming into the phone. I replaced 3 batteries already. I suspect the U2 IC chip as I used to use cheap usb chargers before. Any clue what this could be and who can repair this for me?
If you have already tried 3 replacement batteries, then yes, you most likely have an issue with the charge circuit on your phone. Cheap USB chargers can do that. This requires a micro-soldering repair. You can search Google to see if anyone locally does it. Just search “YOUR TOWN MICRO-SOLDERING”, it should find someone. Barring that, then you can also widen your search as most micro-solderers accept mail-in repairs. There are a few reputable micro-solderers who patrol this forum. You can check out my profile if you’d like, at the very least it will serve as a data point.
