STM32F429 SPI bootloader doesn't respond to Synchronization Byte. What am I doing wrong?

[MSipo]

I'm having trouble getting into SPI bootloader mode on SPI1 using NUCLEO-F429ZI.

I have verified this:

 

I have followed this:

 

And used these pins and SPI mode:

But I still don't get any responce:

Full sequence från me pushing the reset button and my second board sending the Synchronization Byte:

Details when sending 0x5A (Synchronization Byte):

What am I doing wrong here?

I have a simple LED blinky program on the MCU (that it boots to when BOOT0 is low). I can see that it boots into bootloader mode at least beacause it doesn't blink the LED anymore. But I't doesn't respond.

[MSipo]

I made progress. I discovered that it replies after a power on (connecting the board to USB cable), but does not respond after a reset on the NRST pin.

Is the BOOT0 pin only evaluated at power on and not at NRST pin rising edge? Or is the NUCLEO board doing some stuff here ther affects this? How can I make it work with pressing the reset button instead of power cykling the board?

I tried also tried to break off the ST-link board. No difference. And also desoldered the bridges for ethernet. No difference.

It only works if I reboot the board power. If I at the same time hold reset and then release it it will not work.

[MSipo]

I tried to enter UART1 bootloader. I got the same problem there. Only able to enter UART1 bootloader if I power cycle. I posted a question about that too. Something strange with my NUCLEO-F429ZI.

[MSipo]

I solved it. See my other thread about this. https://community.st.com/s/question/0D53W00001pwlAWSAY/nucleof429zi-cant-go-to-uart-bootloader-with-the-reset-button-but-only-after-a-power-cycle-why