The HP Envy 4520 Printer Offline displays a common issue that is related to the HP printer in the operating system. First of all, search the operating system for Windows 10 for up-to-date information.
You must then update the printer drivers mounted on the PC to run the HP printer to avoid the HP Envy 4520 offline error. You can reinstall the drivers from HP’s official website if they are not updated. You can contact a specialist, who can guide you with more comprehensive approaches if any assistance is required.