When I removed my keyboard, all but three of the rivets stayed in even though the heads all came off. My luck...! I didn't want to use the screwdriver and hammer method to remove the rivets, because I was concerned that rocking them out in that way will tend to cause the hole to become oblong, and it may not hold the new screw thread as well. Instead, I used an electronics wire cutter to pull out the rivets. You have to make sure the tool is what is known as a flush cutter, which has the cutting edge ground completely flat. The more common grind is slightly set back from the edge to create a more robust cutting edge, but it will not work here because the tool won't be able to grab enough of the rivet to pull it out. Nor will a large tool, for the same reason, so try to use a 4-1/2 inch or 5 inch cutter. It does not have to be hardened because the aluminum is not much harder than the copper that these tools are designed to cut. You just put the tool completely flush on the aluminum, with the rivet about an...
If you are using a heat shrink iron as David commented above, keep it in contact with the phone for the shortest possible time required to soften the adhesive. At their highest settings these irons can reach over 200 degrees C (around 400 F) which is hot enough to damage flat cables, and distort or even melt plastic components inside the phone.
If you are using a heat shrink iron as David commented above, keep it in contact with the phone for the shortest possible time required to soften the adhesive. At their highest settings these irons can reach over 200 degrees C (around 400 F) which is hot enough to damage flat cables, and distort or even melt plastic components inside the phone.