This video proves that I sometimes still have to learn the ropes. 😯
But in the end it still worked and my tube radio now has Bluetooth.

0:00 - Damage analysis
0:36 - Greeting
1:09 - Unboxing
2:00 - First connection test
2:39 - Measure power consumption
3:09 - Power supply schematic
3:14 - Assembly
3:50 - Is the power supply working?
4:08 - Connections to the radio
4:41 - The disaster
5:07 - Error analysis
5:32 - The new plan
5:55 - Attempt 2
6:09 - final test
7:52 - Conclusion