This step requires the removal of the warranty sticker. Removing the sticker will void the warranty. According to the FTC removing this will not void your warranty.
Locate the sticker in the battery compartment labeled: "En: Warranty Void if Seal Damaged."
Remove the sticker using the PSP Opening Tools.
Under the sticker is a 5mm Phillips screw needed in the next step.
Carefully disconnect the UMD drive ribbon cable from the logic board. Use the PSP opening tools to push the black tabs on the connector horizantally to free the cable.
This connector cannot be removed vertically. Doing so will damage the connector and/or ribbon cable.
At this point it is useful to tape the loose metal parts with some masking tape so they don't fall out whilst you have the PSP the other way up.
I've used this guide multiple times and it is simply the best out there. You should simply title it "PSP disassembly" as I have used it just to take the 2000 apart and not just replace the UMD drive.
This guide was very helpful in replacing the UND drive in my 2000. Unfortunately, it turns out that the UMD drive was not causing the issue it is having.