You do not need to replace the formatter. Power off the machine, power on the machine and when the three lights on the control panel turn on press the cancel (x) button. This will take you into the pre-boot menu. Scroll down to the Administrator menu press enter, scroll down to startup options and press enter and then scroll down to cold reset and press enter.
Your other option under the Administrator menu you can try is to perform a partial clean.
If neither of the options work, you will need to format the drive which is under the Administrator menu as well. On the M551, you need to install a usb stick with the current firmware onto the USB ports that are located internally on the formatter. Power off unit, remove formatter, install USB drive, reinstall formatter, power on, go to pre-boot menu as above. Under administrator menu, select format harddisk, then select the download firmware option, select "usb key" which is last option for firmware updates. After firmware downloads, restart the printer. Once you are sure that everything is working, shut down and remove the USB key.
If you find the information provided useful or solves your problems, help other users find the solution easier by giving kudos and marking my post as an accepted solution.
