@Attila27 Welcome to HP Community!
I understand that you have an HP LaserJet Pro M1217nfw Multifunction Printer. After installing the toner cartridges, the printer is stuck on "initializing" message and does not get out of this.
I recommend you to perform the following steps to isolate the issue and arrive at a fix:
- Disconnect the power cable from the printer while the printer is still ON.
- Disconnect any other cables if connected the printer.
- Press and hold the printer’s power button for 15 seconds.
- The printer should be directly connected to the wall outlet and not to a surge protector.
- Reconnect the power cable to print and the printer should power ON by itself. If the printer doesn’t power ON then please manually power it ON.
If the issue persists then let us perform an NVRAM reset. This reset will completely reset the printer to its original factory settings. I have sent you a private message with the reset steps.
Keep us posted,
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Give us a virtual high-five by clicking the 'Thumbs Up' icon below, followed by clicking on the "Accept as solution" on this post,
Have a great day!