A process for loading a secure memory image for a startup procedure of a microcontroller from an external non-volatile memory has the microcontroller configured to assume a locked state in which execution of any program is prevented pending a restart of the microcontroller when a data section of a secure memory image is faulty. The process includes the following steps: detection of the locked state of the microcontroller by a controller located outside of the microcontroller, institution of precautionary measures that lead to modified read data values of the memory image in a subsequent attempt by the microcontroller to read the memory image; and initiation of a restart of the microcontroller to cancel the locked state, and thus initiation of a renewed attempt to load the memory image. An assembly including a microcontroller, an external non-volatile memory and a controller implements such a process.