Hi @MCMuollo,
Welcome to the HP Support Community
I understand you are facing an issue with your Hard/Full Reset on Officejet Pro 8620. Not to worry I will help you to get a resolution to resolve the issue.
Let's perform a power drain:
- With the printer turned on, disconnect the power cord from the rear of the printer and also unplug the power cord from the wall outlet.
- Remove the USB cable, if present.
- Wait for 2-3 minutes, press and hold the power button on your printer for about 30 seconds to remove any additional charge.
- Now plug back the power cable straight to a wall outlet without any surge protector or an extension cord (This is important) and then plug back the power cord to the printer.
- Turn on the printer and wait till the warm-up period finishes and the printer is idle
Update the printer firmware
- Click here to download and install the latest printer firmware from your product
- Click here to know different methods of updating the printer firmware.
If the issue persists, then please follow the steps mentioned in this document: I really appreciate your efforts. As the issue still persists, I'm sending out a private message to assist you with the next course of action.
Please check your Private message icon on the upper right corner of your HP Community profile Next, to your profile Name, you should see a little blue envelope, please click on it or simply click on this link.
Hope this helps! Keep me posted.
Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Click the “Kudos/Thumbs Up" on the bottom right to say “Thanks” for helping!