[STM32WB55] Unable to connect to the target via USB DFU mode

[OShen.1]

I am working on the STM32WB55 Nucleo board and currently facing a problem. I have erased the whole flash, i.e. all memory locations are reset to 0xFFFFFFFF from 0x08000000 and 0x08FFFFFF. When I reconnected the board under USB DFU mode using STM32Cubeprogrammer GUI, I accidentally pressed "start wireless stack" button then the target is automatically disconnected. When I try to reconnect the target board, it failed and prompted: "Device is under read out protection! If you want to disable RDP please reconnect with Read Unprotected enable":

However, the RDP value that was read after I connect the board again via ST-Link is 0xAA (no protection):

I have no idea why I cannot reconnect the board via USB DFU mode anymore since the RDP value reading is indeed 0xAA (no protection). I need to re-install the wireless stack and FUS firmware but I am currently stuck here. Please kindly advise and help. Thanks!

[Remi QUINTIN]

I am just puzzled by the fact you managed to reset the complete Flash memory to 0xFFFFFFFF from 0x08000000 and 0x08FFFFFF.

Max memory address for a 1-MByte device is 0x080FFFFF.

This would mean you also managed to erase the FUS located at the top of the Flash memory from 0x080F40000 to 0x08FFFFFF.

If it is the case you will never be able to load any wireless FW.

Could you please download the option bytes, especially those related to security?