I assume you've checked the bulbs. If one burns out and the filament holders touch, that's a dead short. Stranger things have happened, and a bad bulb is easy to fix.
I had an instance where my blinkers on my daily driver truck didn't flash on the right side. I was SURE it was the switch and replaced that. Not fixed. I had my camper on so couldn't check the trucks taillight bulbs. Drove from Spokane WA, to Wichita KS manually working the lever for right turns.
Finally had an opportunity to take the camper off and found the two filaments shorted together, so there wasn't enough current to activate the flasher because of the resistance through the turn signal filament AND the tail light filament. Replacing the bulb fixed it up.
