Check if the microphones does not have protective Adhesive. Some times original adhesive is left on phone and new charging ports comes with adhesive on microphones.
1- WiFi greyed out. This is WiFi if issue, try to heat up. 2- try new charging port for charging issue 3- try new battery, if it boot loops. 4- If phone stucks on iTunes logo, this is mother Boars issue. I believe no one will try repair this device as it is very old.
