Connect the printer to a PC via a USB cable ; it should be the only USB device connected.
Search for: HP OfficeJet Pro 8620 firmware 001.1829A.00.bdl (Use reputable printer forums – not unofficial random sites without community validation.) hp officejet pro 8620 firmware downgrade
Downgrading the firmware on an HP OfficeJet Pro 8620 is primarily done to bypass "Dynamic Security" features that block third-party or refilled ink cartridges. While HP officially states that downgrades are not possible through standard support channels, users have developed workarounds using older firmware files and manual installation methods. HP Support Community Prerequisites USB Connection : The printer must be connected to your PC via a USB cable. Ready State Connect the printer to a PC via a