My STM32 Tester finally arrived, and 12 rejected MCU’s which is ca 40% of all STM32F405’s I had is the result. The sent me a different tester than I ordered, but it did the trick. One MCU broke under testing as well.
10 x STM32F405RG cost va 45.- USD from China and ca 90.- USD from Farnell in Norway. With 40% loss and the unknown of factory rejects I can as well just order from Farnell.