To acquire the reset  What you need to know:

Model (the model is indicated correctly on the body of the printer, but not on the report!),
Serial Number (Serial Number);
CRUM (toner chip number);
Firmware Version.

This information can be found in the reports: Configuration Report and Supplies Information.

HP 408dn Report Printing

Configuration Report: From the printer control panel, click Menu [...] > Information > Configuration and print.

Supply Information: From the printer control panel, click Menu [...] > Information > Info Suprim and print.

If you are unable to print the report, the data can be verified by remote access. 

I received the files, what now?

First of all prepare the printer to receive the file:
With the printer off press and hold the X button and press and hold the [POWER] button, after ~ 1 sec release both buttons. the message "Download Mode" will appear, click X again and it will appear the message "Wait Image". This process should be done quickly.
The uploaded compressed file contains:  "FIX...",  "usbprns2" and INSTRUCTIONS.
With the printer in download mode as described above, just drag FIX over usbprn2
 

After this procedure, in a few minutes the printer will be ready. restart. Remove the toner chip and try printing without a chip. From that moment on, do not use a chip in the toner anymore.
 

CAUTION!!! After successfully reprogramming the printer, remove the chip from the cartridge and store it somewhere safe (the chip). On all the cartridges you buy for use in the printer, the chip must be removed or sealed. If you If you accidentally insert a new cartridge without removing the chip, the device will be reset. To unlock it, do the reset using the same chip.

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