On reassembly, you have to position the steel cap in the center of copper contact ring, placing plastic sticker into its respective cavity on the back of the button.
Press the sticker firmly into its place. Don't worry if it doesnt stick all the way round. its position under the glass keeps the details in place. Again, try to prevent touching the glue while disassembling.
Congrats! Re-assemble your device and enjoy your revived home button!