Check It, one guy has the same problem like you and looks like is a missing screws and plates. iPhone 7 NFC(Apple Pay) not working after battery replacement UPDATE: This is the NFC antenna make sure that is not broken and the screws are well, sometimes when you remove the top screw, the bottom one come out, and that can damage the antenna or can’t make contact to the pad on the board.
If you want your computer more faster replace the 1TB HDD for a SSD, that will make your computer more faster (I think x10 faster). If you want more Software load you can upgrade your RAM. Check your Task Manager and probably you will see your Hard Drive working at 100%.
You have to replace that small burned component (micro-soldering skills required). If you don’t have experience take it to a computer repair shop. Replacing that component will take 5 mins, and additional inspection looking for short circuit another 10 mins.
Camera will focus the closest thing to it, if the outside glass has dirt will focus it, if you already replace it make sure that everything is clean. If a cleaning job does not fix your problem can be a micro-soldering repair.
Yes, it is possible, the microphone is really close, cover it when you are applying heat. You can't see the pins when you are removing and installing the new port, so you need to do a clean job and all pads needs to have the same amount of tin.
If you are fixing one glass only it is not worth. You need a hot plate and metal wire to remove the front glass, and optical clear adhesive to put a new glass on it. The "Glass" needs to have the digitizer (touch screen) atached it, a tempered glass or screen protector wont work. You need tools, screens for practice and hours of work.