There are 6 screws to open the hood: Two on each end cap, and two on the bottom trim. They are all hex screws, so I had to go to Lowes and buy a 4 bit set (the smallest ones they had).
The two screws on the bottom trim were the hardest because of the space between the cooktop and the trim. I had to use a wrench to hold the bit, but once I got it started I was able to finger loosen.
Remove those screws, and the control panel (on the older models) is one single piece. It is removed by 4 screws. The scews on the left hold the ground and the "wire holder" - you might want to remember how those go in.
The wiring is pretty easy. But, don't unhook anything until your new parts (plural) arrive since everything is marked pretty well on both the old and the new control panel.
When your new control panel arrives, it is simply matching the connections (B1 still goes to B1, B3 to B3, etc).
The missing piece is the overlay. I haven't received mine yet, so I can't tell you how hard it is to replace yet.
There is a great schematic of the hood at: JGBP34GEV3WH Range Stove Oven Hood COOKTOP Parts