Its pretty simplistic inside once you get it out. But its a total pain in the ass to remove the switch. I had to dremell slits into the security bolts and then finagle the bolts out like bad screws.
Anyway, consider contacting the dealer and seeing if they will work out a goodwill replacement on the part (not labor). Triumph did that for me. Then I just swapped out the new electrics with the old electrics, keeping the same keys, gave Triumph the dud, and mine has worked flawlessly ever since.
But I'd be real careful if you go anywhere. Once mine gave up the ghost it was just like you say. Turn the bars one way, she purrrs. Turn them another, nothing. Total blackness. It was disturbing, and I couldn't even drive the bike home. Had to tow it.