Did something ***, now no flash memory.

[brohr01]

I was trying to change an option byte from the embedded bootloader of an stm32u5 over canFD.  Long story short I sent it some messages that were not formatted correctly and It looks like I have bricked the chip.  Trying to connect in stm32cubeprog with my st-link over swd I get
Error: ST-LINK error (DEV_TARGET_HELD_UNDER_RESET)

I have measured voltage on the reset line and it is 0.0v, I tried to pull it high through a 10k resistor and I still get the same error.  The most interesting part of this is when I ran "st-flash reset" I get the following output

st-flash 1.8.0
2025-01-26T20:22:12 INFO common.c: STM32U5Fx_U5Gx: 3026 KiB SRAM, 0 KiB flash in at least 8 KiB pages.
Failed to reset device

Notice the 0 KiB of flash, but it still identifies the chip and sram.  Any other ideas to try before I desolder and replace the chip?

[Uwe Bonnes]

Does the target get hot and suck substantial more current? Then high voltage on some pin killed your chip.

[Andrew Neil]

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@brohr01 wrote:

I have measured voltage on the reset line and it is 0.0v, I tried to pull it high through a 10k resistor

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So did the pullup actually change the voltage at the pin?