You made me curious, so I went out and looked. That panel does indeed allow access to the side of the WH and surprise what looks to be the control board is in a plastic enclosure just laying on the wire bundles (I pulled it out for the photo). There is minimal access to the back of the WH, maybe can get to the hot side check valve. In the photo the control board with the red ignitor wire is to the left, in the right background the red/hot water connection can be seen as well as the blue/cold water connection. The right side of the area is the engine compartment/radiator wall, washer is directly above.
2018 Tiffin Allegro Red 33AA
2006 Jeep Liberty