During reassembly, perform the following to clean the thermal paste:

Use the flat end of a spudger to scrape off the thermal paste on the bottom of the logic board.

Clean any remaining thermal paste residue with isopropyl alcohol (>90%) and either a coffee filter or a lint-free cloth.

Repeat the cleaning process for the thermal paste on the frame.

During reassembly, follow this guide to reapply thermal paste to your device.

When applying new thermal paste, use the flat end of a spudger to spread it evenly across the logic board. Try to match the original spread.