We have an HP OJ 4710 that has been in use for a few years without any major issues. After this weekend, the printer was stuck off (on button did nothing) so pulled the plug, waited 30 seconds, and plugged it back in. Now, it attempts to start up, showing the bootup screen for a couple of minutes, then it blanks and restarts. The longest I have let it go on this cycle is around 30 minutes with no change in status. I have unplugged everything from the back, tried just the power and ethernet cable, but it will not get past the startup screen without rebooting. The printer is not recognised in the software with either USB or ethernet cable attached.
Here is what I found corrected my issue. First I tried unplugging the power, phone and lan connection (I was not using the wireless function). None of this powered off the printer. As soon as I plugged the power cord in the printer began showing the Invent screen and kept on without interruption. I'm using this printer in a small office network. The printer is connected to a 4 port switch which is then connected to a router. The network is set up for DHCP but I've given the printer a static IP address. When I looked at the switch I noticed the link light was not on and thought the printer was not 'speaking' to the network. After powering down the router, switch and unplugging the printer then cycling back and turning on the router, switch, and plugging in the printer the printer did not stop it's looping and the link light was still not on. Anyway, I let the printer keep on doing it's thing (looping with the Invent screen) and I figure at least 15 minutes or so went by when all of a sudden the printer completed it's power on cycle. Once that happened I went onto my PC, into Settings/Printers and Fax. Right click the printer (4710) and click on properties. Go into the Ports tab and click on the port assigned to the 4710. Click on Configure Port. I noticed the IP address had an alphanumeric value HP###### in it. I changed the IP back to the static IP address that I originally set. I went over to the printer (who's IP address was not set even though DHCP was set) and set the IP to the same and from then on all worked fine. I did have to go around to the other PCs in the office and change the Port setting (they still showed the HP#####). Now if you end up in the situation where you can't get the printer to power on even after 15 minutes or so, try going into the Port settings as I've described above from your PC. Unplug the printer and change the port setting from your PC then try turning on the printer again. This may not work as I believe the printer needs a valid IP from it's configuration menu setting so that it 'speaks' to the network. By setting the IP / Port at the desktop, this allows the PC to 'talk' to the printer over the assigned port.