That sounds like one unlucky event.
It is very surprising that the back screen is not worth replacing but then perhaps it depends on whether the water entered the back panel or got into the camera itself and so stopped the screen working. I have used my Pentax gear in all sorts of weather with no problem, as I think most users have, but immersion is a different matter.
How effective is the weather sealing? I guess we will only find out as time goes by and if more dead cameras or components start getting reported.
Sometimes given time and drying things come back to life but it sounds like your accident happened a little time ago. I've just remembered, I managed to get water into my little waterproof Optio once by jumping into a pool with it. The impact with the water forced the water past the seals, could this be what happened in your case? I was lucky, despite it stopping working and water running out when I opened it, I left it open with battery and card out in a warm dry place for a few days, it came back to life and still works today a couple of years on.
I still can't believe it means your whole camera is only fit for the bin! Worth getting a second opinion?

Particularly like the first one with the people moving. All lovely.

What a lovely, beautiful series. I like what you're doing.

If the lens and camera worked together well in the past (or even if not used together before) it may be the simple job of cleaning your auto focus sensor. It is located in the bottom of the camera body, lock your mirror up as if cleaning the sensor and you'll see it nestling in the bottom of the camera give it a brush and a blow and see how you go! It is the easiest thing to try first.
Good luck
Nigel

I notice that special deals for the K3II with free grip have started appearing in Americaland, this can often be a sign of an announcement of a replacement camera in a few months time. But not always!

A nice set of images of a scary looking walk. Where in the Pyrenees is this walk?

All I can say, my 18-135mm came with my camera as a kit. I assumed I would just sell it on as I have the posh f2.8 zooms + others. NO WAY am I selling it, light compact and a good performer in my opinion. Mind you my KS-2 and 18-135mm together were not that much more than the price you quote above for the lens alone, I just happened to need a new camera at the right time.

With your Q suddenly turning itself off, could it be your battery is starting to fail? If its voltage is fluctuating. It is a long shot. Do you have a spare battery and have you tried it?
I did have the problem of my Q not keeping the correct time and date which was fixed when I formatted the memory card, not a connection one would assume.

Good luck, wishing you success.

A nice set.
I love fresh little sardines, that picture makes me want to light the BBQ.

Another very enjoyable set. Some great observation and timing.