Intermittent electrical issue

Good morning all

Just bought an 08 plate micra auto for my elderly mother.

Starts and runs fine, she likes it, apart from an intermittent electrical issue...

At times, everything works fine.

Then, for no apparent reason....

The nearside indicators react with the nearside brake lights, alternately flashing. I've changed the bulb, no change.
At the same time, the key wont operate the central locking remotely (new battery was fitted to key). The button by the handbrake operates it ok.

Now .... this appears to be controlled by the heating (climate control) system.... there are times when you leave the car with it switched off, only to return to find everything on and the fan blowing full blast.
Fiddling with the controls here, at random, can change the state of the rear lights/indicators/locking from working to not working and vice versa.

When nothing is working, and with the key removed from the ignition, there is a flashing key symbol to the left of the speedo. Sorry, cant remember if this is flashing if the other systems are working.

As an aside, and I dont think related, the rear parking sensors have never worked.

I'm lost. It is going back to the dealer on Thursday, but obviously everything will work fine for them....

Any ideas?

Thanks all.
Have experienced heater issue here with rear heater and the ac button. Both coming on and going off sometimes the light may flicker after turning on and off. Not much else happens for me the battery was slightly drain when I first got the motor.
Would suggest try remove the negative terminal on battery then wait for 15 mins and replace test see what happens. Save your code for radio if possible you can find out how on here how that may be done. I have no idea since didn't require that.
hopefully intermittent problem will be solved here.
As for me I was wanting to stop rear heated screen from being on so I did not have to keep bringing the battery indoors to charge.
So I just turned both off and managed to get the button to work again. For rear screen heater the ac I am not really interested in so that's turned off till summer time. I may try it again it does work just don't really need it often.

Another thing I would check ground points are clean. Another good place to check also is the rear door wire loom for cuts in the cables i'm sure this has already been discussed on here and you can key that in to search to learn more(again this was not needed for me but I still feel this could be a problem area).
I'm sticking to how it is now everything I need works properly as far as I know in my case.
Hope you get it sorted out soon