Measure the hatch precisely before ordering. Don't start the job until the hatch is present. The electrical hatch should not be left open, as rain, dust or other debris may get inside and cause shorts or other damage.
Remove the bolts or screws surrounding the perimeter of the hatch with the drill and sockets.
Break the perimeter weathering seal with the pry-bar or hammer.
Peal the hatch off and away from the RV.
Scrape off the old, excess weather sealant from around the port.
Apply fresh weather sealant, like caulking, to the edge of the port.
Push the hatch into place, firmly against the sealant.
Reattach the screws of bolts around the perimeter.
Push the sealant into place and against any areas not covered around the edges of the hatch. Apply more sealant if necessary.
Slide the hatch door into place and make sure it shuts flush and latches.