I had some issue with my rubber button on the hatch. I see a few people replacing this for around 50 bucks. My solution is cheaper & you don't really need to take anything apart other than the two screws. I bought a sheet of silicone gasket seal on amazon. I think it was 10 dollars. Initially I was going to use an old bike inner tube, but having gone tubeless with my bike I couldn't find any old tubes to use. Anyways, all you have to do is: get an L-shaped screw driver and remove the two screws, they are very soft metal so make sure you apply pressure on the screws while you turn it. Also once the two screws are off, carefully pry the button down. As you can see the two screws expand the plastic housing of the switch. if you need more room to work, you can carefully pry the blue electrical switch from the housing. That is what I did so I can take the housing to my garage as it was very hot outside. Scrape all the black goo from the switch housing. I cut the silicone to fold around the switch and put everything back. The Sheet is pretty big so take your time and make one which will wrap around all 4 sides. Here is the results. I am planning to replace the two screws with something easier to remove in the future if I have to do this again. I don't know how durable this material is in the sun.
If you would've called toyota hq and complain about this sticky button, they would have covered the cost of the repair.
WAAAAAAAAAAAAAAAY too easy. You'll enjoy post # 75 How to Replace the Hatch Opening Switch | Page 4 | PriusChat