It's pretty common, here is how I dealt with the same problem: Portenta H7 bricked - Hardware / Portenta - Arduino Forum . Basically, the STM32CubeIDE only knows about the MCU not about the PMIC that powers it - for that you need the BSP that Arduino provides including the boot ROM that configures it. When you overwrite the Arduino boot ROM each time when downloading code, the MCU does not get 3.3V but 0.17V.