Unable to reset RDP from BB on STM32F407G Discovery

[Robmar]

After using STMCubeProgrammer 2.21 to set the RDP byte to BB, the board works fine, but Cube programmer is later unable  to access the board; I've tried different modes, under reset etc.  The disk folder shows when plugged in to the USB with FAIL.txt listing and a connection error message.

This only started happening after updating the programmer a week ago.

Has anyone had this problem and found a solution? Thanks

[Tesla DeLorean]

With BOOT0 HIGH you might be able to walk it out via the System Loader off the UART. Watch how PA9/PA10 are wired, and the capacitor.

Could try updating the ST-LINK to a Segger J-LINK OB firmware, as Segger has had tools previously to unlock/mass-erase STM32 parts.

[Robmar]

Yes but this has never happened before, only since the last update.  The IDE seems to have been updated with a different link firmware than the Programmer, so swapping between the two both prompt to update the link firmware, its a bit of a mess.
Maybe its the link firmware used by the Programmer, someone must know.  I don't want to start having to do a batch of 200 boards with the UART

[Robmar · Accepted solution]

Manufacturing fault found on a batch of STM32F407G-DISC1 boards, after debugging the hardware SB9, a debug mode link, is open circuit on all the boards suffering from the link failure ("FAIL.TXT").
I attach a photo.  Repairing link SB9 fixed the link-fail condition on all the faulty boards.

[Mike_ST]

Hello,

Thank you for the feedback, this point is being investigated internally.

[Thierry GUILHOT]

We are very sorry to hear about the problems you have faced and we thank you for sharing this with us.

In order to further analyze the problem, would you please let us know the board serial number? It is printed on a label with a QR code.

[Robmar]

Thanks, these things happen, what's worrying me more is the state of the Cube IDE and software packs, which makes developing a functional product very difficult and more costly than necessary.

This is the batch number and one of the failed boards serial:-

4000293 1901 001532 2224

C223802587