I'd probably try a few things (these are total guesses on my part, not experience, use or not use as you please):
- I'd get an OBDII device (not super expensive) and see if you can pull any codes. If the car is this disabled, the OBDII should show one or more codes. I'd then google whatever codes it finds. If you write down the codes first, you might try clearing them (not that I think that will work, but I'd be desperate for anything to try which is the reason I mention).
- I'd try pulling some fuses if no useful data from the OBDII. Typically in the passenger compartment and in the engine compartment. I'd likely just pull one at a time, test, if no-go, replace and try another. Rinse and repeat. Yep. Super time consuming. But if you've got nothing, it's worth a shot. On conventional cars I've solved electrical problems by finding the "offending" fuse then being able to figure out where the issue was. I'm not sure if this same method can work on Clarity.
- Are you physically close to the Honda dealer service department by some stroke of good luck? Consider hiring a tow truck to deliver the Clarity in for a repair quote. This may cost a few hundred dollars or more just to find out what's wrong. Much depends on how far you'd have to tow.
Anyway, just some shots in the dark here. Wish you luck and a good outcome.
