is it the case that the camera does not work without a cable? must it always be connected to the power supply?

i have the screen and two cameras that are displayed at the same time. now the screen has broken. can i buy a screen with a camera and link my old camera so that it is displayed at the same time again or do i have to switch between the cameras myself or do i have to buy the whole set again with 1 screen and two cameras if i want to have both displayed at the same time?

Can you open the monitor to change the battery? After 2 years, the battery is now completely dead on me, but everything else still works great. I tried to lift it up but it seems to be screwed in at the corners. Does anyone have any experience

Does anyone know the dimensions of the camera?

Can you upgrade later and monitor a second children's room with the extra camera? Is there then a function to view images from both cameras at the same time?

Is there anywhere to buy just the wall mount for the camera? Or does anyone know of a universal wall mount?

What about the data security of the camera and does each device work completely without an internet connection? I have one of the Vava Home Cams (a story all its own, if you want drama, you're invited: https://www.kickstarter.com/projects/2130897358/vava-home-cam-wire-free-security-with-a-one-year-b/comments ) and I assume the software/firmware is similar. With the Vava Home Cam, when I had a problem with the firmware, customer support had to tinker with the camera directly via the internet - and without me ever approving or allowing anything first. I couldn't update the firmware myself, it was done directly by Vava. Now I'm wondering if there isn't a danger that something like that could happen here too... or if the camera is safe?

Power adapter? CH plug or DE plug?

Can this product be used without WiFi?

Is the sound transmitted continuously, or is it possible to adjust this somehow through the 'sensitivity setting' so that the sound is only transmitted above a certain volume?