ColinBarber

I don't think you are able to - I've amended.

A lot of dealers don't set/reset those, they are more of a DIY reminder.

Yes, the 12v Battery isn't powerful enough to power the air con system for any length of time. The vehicle will go into Ready mode and the petrol engine will come on/off as required to keep the hybrid Battery charged.

These work well if you want to peridocially and manually keep an eye on the voltage but you would only get an alert if you are stay within Bluetooth range so isn't a good solution if you aren't taking the time to check and just expect a automatic notification that its time to charge the Battery.
https://www.amazon.co.uk/Battery-Monitor-Campervans-Compatible-bluetooth/dp/B08VHMJYXY
 

sounds like one of the servo motors is running - possibly the gearing has failed or is slipping on the shaft so the motor keeps running. Using the controls you should be able to determine if it is the motor that controls the cold/warm air mix or airflow positioning. 

All grades come with Dynamic Radar Cruise Control (aka Adaptive cruise control). Speed can be linked to speed sign recognition and also has Curve Speed Reduction to slow you down for bends.

I think the ETCS circuit only connects to the engine ECU so that one is easier to fault find. Disconnect the Battery and measure resistance from that fuse to ground to see it if is shorted, and then do the same with the ECU disconnected. You potentially have blown the ECU, or there is a short in the wiring loom from melted insulation.
Also worth checking the 120A alternator fuse hasn't blown.

Technically you need washers because the vehicle is fitted with HIDs. You could potentially fail the MOT without them being there and working.