Yup, mains electricity is one of those things where the rule of "if you don't already know, I'm not going to tell you" applies in force.
This seems like a strange design to me. There are times when you'll want to take the cover completely off of the hot tub (party, etc) and not want it to slowly start getting cold. If I was fixing a hot tub with this "feature" I'd probably wire around it. Or would it maintain temperature, but not allow any changes when the cover was off?
Sorry, by cover, I meant the cover to the compartment where the pump, heater, and controller board are located. If those are accessible, and it's conceivable that someone could splash enough water over the side for it to contact electrical components - e.g., nearly submerge the pump motor - that you'd want those components protected from major sources of water. Thus, on the board I worked on, it would be difficult to trouble shoot, because nothing will work when you're looking at it (unless you have a magnet.)
And, I forgot to finish my thought above - on installing the electric - if the board is fried, it's possible to simply buy a used, working hot tub on Craigslist for less than the cost of the new board.