STM32H757 ST-link locked by ITSELF

[Leoq]

I am working on STM32H757i-eval board. It worked well until this morning when it displayed "Error in initializing ST-Link device, Reason (4) No device found on target" at the time I was burning an image to it through the ST-link on stm32CubeIDE. Then I used stm32CubeProgrammer to connect the board with st-link, it displayed the error "open_comms, Unable to detect DBGMCU Mailbox".  Anybody has experienced such issue ? I am afraid that if it is able to locked itself, perhaps it would unlock by itself on a product when I intend to lock it to protect my image !

[Tesla DeLorean]

Hard to say, these parts can get into problematic states if the LDO/SMPS settings are wrong.

You could try the following technique. With the BL_BOOT0 jump in place to pull BOOT0 HIGH, power cycle* the board completely several times. * Remove all power sources.

Then try to connect with STM32 Cube Programmer, if that succeeds, do a Mass Erase. The ST-LINK isn't designed to be shared by multiple applications / tools concurrently.