TL;DR : Device couldn’t be charged to full. I replaced the voltage divider responsible for battery sensing. However more investigation, and everyday use is needed to fully evaluate this fix.

I’m a total newbie when comes to cellphone repair, but the fix presented here worked like a charm and is relatively easy if you know how to solder. I’ve came across the solution on the iRepair channel on YT and below I post some photos from a microscope with a super brief explanation which the video lacks. First disassemble the phone and take a look at the “reference” image below.

Sometimes it’s inconvenient to develop a driver for some peripheral or sensor in-tree. As far as I was able to research (bare with me, I’m relatively new to Zephyr), the Zephyr RTOS modules are the way to go in such situations. First, a bunch of links that pointed me in the right direction:

These are instructions that worked for me when faced with a problem of modifying option bytes in stm32f042. The thing I was trying to do was to turn off BOOT0 pin support (PB8 in my chip) which then would eliminate the need to pull it. Then I could use this pin for something else, for example as a CANbus canRx input.

This is a step by step tutorial on using STM32 (stm32f407vg to be precise) under Linux (Ubuntu 18.10) and other tools (QtCreator and CMake) that I use in my everyday work. In this article we will compile simple LED blinking program and run it on the STM32F4-DISCOVERY. There may be easier ways of accomplishing this though. Paragraph titles ending with an asterisk are optional.