Unfortunately, speaking from the point of view of someone who does understand how these things work, there often isn't any other recourse when it comes to laptops. A lot of laptops have everything integrated into one board, non-removable components and all, and if you've spilled water over some live tracks and they've shorted, sending higher voltages into the wrong places, you could easily have destroyed something that's soldered onto that one board. There's no choice to replace it, and the board itself will cost a couple of hundred quid in most cases. At least!
While I have nothing but contempt for the PC Worlds and Currys of this world, who often charge ridiculous sums of money for doing a rubbish job at simple things like installing hard disks or setting up Windows for people, it's entirely possible that the "board-swap monkeys" were simply wary of wasting an hour of their time disassembling, cleaning, carefully drying off and reassembling a laptop only to find that the board's fried, needs to be replaced and the customer isn't willing to spend the money to do the job.
