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I had an iPhone 6s with a broken screen that was functional so I tried replacing the screen. When I had the phone open I replaced the battery as well. Now the phone will only power on and stops at the Apple logo. I have tried the suggested reboot tricks (holding the volume button) but nothing happens. I can hold the power and home button and it will power off but automatically reboots and gets stuck on the Apple logo. I tried putting the broken screen back on to see if that was the issue but it does the same thing. Is it a bad battery? Or was the logic board damaged during the replacement of the battery and screen? Thanks for the help in advance.
You may have damaged the logic board during your repair. First , did you disconnect the battery before working on the screen? That will usually cause issues with the backlight circuit but it can also cause any number of other issues. What you need to do is closely inspect the logic board, preferably with magnification. Focus on the connectors, flexes and the components surrounding the connectors. Look for any missing or dislodged parts, tears in the flexes, damage or debris in the connectors. Depending on what you find, it may be easy to fix (torn flex - replace the part) or very difficult (missing or damaged components).
