Sometimes easier than you think....
The power button fell out of my Moto G4, this was very annoying as it was the only way to wake it up. A shaped wooden coffee stirrer becam essential to use my phone. Eventually I found a replacement button on the internet and ordered it at the extremely overpriced £6. I YouTubed how to repair it and for the very detailed and long process I ordered the right sized torx driver and other stuff.
Before I started the strip down I watched the video more closely. I soon realised the whole point of the strip down was to remove the old button, well mine had already removed its self, refitting simply involved pushing the new one into the empty hole, a satisfying click and done. Total actual repair time <5secs.
YouTube can be too helpful sometimes :)