HP Color LaserJet Enterprise M552dn Lost password

[lmccutcheon]

I have a HP Color LaserJet Enterprise M552dn which has been working perfectly for the last 6 years. However the person who initially set up the printer cannot remember the password, indeed he claims he never set any password.  I have tried every possible combination in an attempt to access the system, even updating the firmware, all without success. Does anyone know how to do a complete reset?

[Repairatrooper]

If you download the firmware readme file, the instructions for accessing the preboot menu are included in that file. Once you are in the preboot menu, select partial clean from the options and then restart the printer. This will clear the password and all other settings.

[lmccutcheon]

I don't have the readme file, just the checksum.txt and the bdi file. 

[lmccutcheon · Accepted solution]

Finally got the issue resolved 😊.  I had seen a thread which said to press the power button and the cancel button simultaneously, but this is incorrect!  Others advised to press both and hold for 15 seconds, this is also incorrect!  I managed to enter pre-boot by first pressing and releasing the power button and then, once the logo and 1/8 appeared, pressing the cancel button once.

Press down to administrator,  OK, press down to Start Options, OK, press down to cold reset, OK, Home button and OK to continue.

It looks like nothing is happening but about 15 seconds later it reboots to factor defaults and asks you to select language etc.

I can now access all operations from the printer web page.

Thanks to everyone for their help