Wiha 4PL driver for these screws.

It is not exactly clear how the keyboard is removed and how the new one is secured. It looks like a soldering iron is used to heat the plastic tabs to remove the old keyboard. But is it necessary to re-melt the plastic tabs after putting in the new keyboard or does that not work? It looked like in the video some of the spots were re-melted on the right side but not everywhere. Will the metal plate and screws hold the new keyboard well enough?

I think you mean 6mm screws, not .6mm.

HP lists the screws on the back cover as size pm1.9x5.6. What is wrong with HP that they would use such an odd size? I tried 2x6mm and they seem to work fine.

Who was the idiot who designed this laptop? Remove the motherboard to replace the battery? Unbelievable.

This guide comes up when I click on “keyboard replacement.” Is there a guide for keyboard replacement? A search does not find one.

What is the purpose of this piece of foam and is it necessary when replacing the hard drive with an SSD?

I have stopped using brackets for most SSD replacements. I bought some circular hook and loop dots with strong adhesive and merely velcro the drive to the case. The cables are long enough to allow the drive to sit flat against the case if you turn the drive upside down after attaching it. Otherwise, the data cable is too short. SSDs are so light that there is no reason for over-engineering the attachment. Most tape is not strong enough but two velcro dots work great.