A client device includes a flash chip for storing firmware and a microcontroller for storing an image in read-only memory. The image corresponds to an accurate representation of firmware. When the client device is powered on but before the firmware is executed to boot the client device, the firmware stored on the flash chip is compared to the image. In the event that the firmware does not correspond to the image, the client device is not booted and the firmware is overwritten with the image. The client device may then be booted using the flashed firmware. To update the firmware, the client device may receive a new image from a server. The new image is stored in the read-only memory of the microcontroller. The firmware may then be re-flashed using the new image.