The cause of this is probably faulty wires.
I would recommend:
Opening it up and fixing it yourself. I’m guessing there’s a faulty connection near the top left hinge, maybe a power cord or ribbon strip that isn’t connecting fully. or,
Take it to an electronics repair store. You'll get the same system back, but fixing a broken system may not fully stop/prevent issues as much as a Nintendo replacement would. or,
Try cleaning the R and ZL buttons, something like Falcon electronics duster cleaner would work for this type of situation.
If none of these work then your system might have a defective motherboard, the only ways to fix this would be to send your system to Nintendo for repair or check it with an ohmmeter.
Hope this helps (: