307 cc Electrical problem (with video)

Good morning everyone, I have a Peugeot 307 cabriolet (model 2008) and it is totally crazy, probably an electrical problem.

The problems that have occurred so far:

1- The key does not lock / unlock the vehicle, if you unlock it (it triggers the alarm) and try to start the car, it will not turn on.
Temporary solution to this: Open the hood, disconnect and reconnect the battery.

2- Everything works (after reconnecting the battery), the car turns on, the lights and controls work, ONLY, the sliding roof does not work, it shows "roof malfunction" (or something like that).

3- This problem is the most common, when you switch on half the key, all electronics work normally, all the commands (roof works, light, mp3 player and everything). When you turn on the car, after about 2-3 seconds, the light comes on automatically, the gas display goes to the minimum and after 10-20 seconds the car turns off and does not respond to any command, you must reconnect the battery.
Note: If you remove the key while the car is on, it will not turn off ...

Video: This video shows the third problem mentioned above.

Link of video: youtu.be/hwSpnkbYNcY ( I can't post the link because the forum doesn't allow me because I'm new in forum )

The question is: What's the solution? What's the problem? Which component should I buy? Thanks a lot.