You will have to open the phone up, disconnect the battery then screen and front camera, now disconnect the rear cam and remove it. Now you have two options, either replace the lens glass only or the entire lens with ring. I advise the lens only, to do this, heat up the lens and push it out(from the inside), remove any remaining glass and adhesive from the lens ring, apply a small amount of glue to the ring and seat the new lens. Allow time to dry properly before reassembly (if not, then the fumes from superglue will fog the new lens). For lens and ring you will need to break off the rear cam retaining bracket from the outer lens ring using pliers, there is a risk doing this that you may damage the glass back (though I have never broke one).
the 7 has 2 white dots on the shell that should line up with 2 holes in the charge port flex (near the connector end), this is so they line up, if you having problems getting them lined up then unstick the charge port flex off the shell and line the holes up with the dots, you may need to remove the loud speaker inorder to adjust the flex correctly. if you have messed about with the connector too much you may need another charge port flex or it will keep popping off.
first thing, try a hard reset. (press volume up, volume down, then hold power button until apple logo then release.) if this doesn't work then try reseating the vibrate connector, if that doesn't work then you may need to transfer the data from the old vibrate to the new one using a eprom data transfer tool. if that doesn't work then try a new vibrate and lastly a new charge port flex.
I suggest trying a new front cam, this may resolve the boot loop just not the home button. you could try reseating the home button flex`s and trying a new screen to fix the home button but I just maybe that the homebutton is broke.