Joe Gon When you flash the stm32f411 or anorther stm32 you need to fill ALL memory with 0 using stm32CubeIDE, because the Stm doesn't have EEPROM memory like arduíno Mega2560, the board needs to simulate a partition and store tablet values! If you flash a Blink led example after flash speeduino when you return with speeduino the firmware bricks!