Hi,
I don't thing swap of STM32 could prevent it from working.
Did you follow the STM32 programming process ? You need to put chip into upload mode to accept incoming comms from progamming tool. Here are the steps :
1. Press and hold BOOT0 button
2. While holding BOOT0, press and release RESET button
3. Release BOOT0 button
Now STM32 should be in DFU mode and accept firmware over UART1.
01' 9.3 SE Conv - AS3 - Nexus 5 Android M 6.0.1 - BlueSaab v4.2 + Amp - Latest CDC repo.