Golf 4 1.9 tdi 99r: Issues with Ignition Switch Beeping and Rear Window Heating Button Backlight

Hello, for some time I have stopped beeping when I forget to turn off the lights and take the key out of the ignition switch. The problem is disputes because I got used to it and I forget to extinguish it.
At the same time, the backlight of the rear window heating button stopped working. It normally glowed red when pressed glowed yellow. Now it glows yellow all the time, and when pressed, also yellow, but more intensely.
I bought the second button and then the same.
What to check first before replacing half a car.
greetings

The first topic, a difficult matter, but because there are thousands of topics ... The second topic is at least spring fuses?

No basic things like fuses checked. I also checked the diode in the switch because I thought it was burned but it works so I thought that maybe something else fell so I bought the switch but unfortunately the same. I think now that 3 things have fallen at once because there is also a backlight of the air supply knobs, but only the bulb burned there.
So, the buzzer from the lights, the switch from the windshield and the airflow backlight went off at the same time. Is it related somehow ?? I don't know if it's a coincidence ???
The most important thing is where to start your search.
Greetings

Read the forum and turn on your thinking. You have hundreds of hints.

I don't understand the search, I can't find anything
Added after 22 [minutes]:
I found some info on the vwgolf forum only that they write about 2 bugs everywhere. The micro switch in the door lock, or the buzzer in the clocks, I tested the clocks with a vag and I replaced the micro switch because it was damaged. I replaced it with an electric spoiler switch from Corrado because I had one, the light in the door and the cabin works, so I think it's ok.
Ps my golf is naked without the control unit and windshields on the crank, so I will not check vagiem again.
ps2
with this backlight of the window heating switch, I have no idea where to look.

After replacing the rear window heating switch, the same thing, i.e. no red backlight - from what I was able to find on the network, there is a wire break, probably at the flap. (I haven't done it yet, but to cover)
the only thing left is the signaling of the lights on after removing the key someone something ???