Chosen Solution
I replaced the full from screen of my iPhone that includes the front camara. After that, the phone does not turn on if I connect all the cables. However, if I don’t connect the from camara cable the phone works partial if I leave the lighting cable in. In addition, when it is on, the phone show that the phone is 0% charged. Than you.
For the screen, does the original screen work properly? If it does, then it could be an issue with the replacement screen. Also, replacement screens with the front camera pre-installed have a lower quality front camera than the original camera so it’s always better to transfer over your Apple-original FCAM to the replacement screen. Defective FCAM’s can cause boot issues. For the charge state, on the iPhone 8 series of devices, there are some tiny electronics components right next to the display connector and close to the battery connector that are part of the communications line that connects the battery data to the CPU. See the highlighted components below:
These can be accidentally damaged or dislodged while replacing the battery and is often called “pry damage”. Take a close look, preferably with magnification, to see if everything is as it should be. Any missing or damaged components will require a micro-soldering repair.
