HP 7780 says "turn power off then on again"

Best to first if you have not done so---UNPLUG the set for several minutes and plug back to power to see if that fixes it (it does a lot of the time especially if you had a power outage).

Just restore your phone to factory settings. It is mostly a software problem. After setting it to factory settings, it must turn back again. try it. just save your important files first. do backups with your messages and contacts and other stuffs in the phone memory.

Have you tried these solutions?

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00489814&cc=us&lc=en&dlc=en&product=3204785&tmp_track_link=ot_search

Hi Good day!!!
Maybe your print head is clooged (red)
Then most about 98% are more likely to be an ink clog which just needs to be unclogged using something like print head cleaning solution
Basically, if a print head has been left unused for some time... moisture inside the ink begins to evaporate and instead of liquid ink, a thick inky jelly begins to form inside the print head.

When this occurs white lines appear in prints and most people not realizing the problem, will replace their inks... But when that does not work. Some assume they have an electrical fault, and replace their print head, others will replace their printer !

But provided there is no obvious print head damage? In 98% of cases it simply needs a little patience and print head cleaning solution injecting directly into the print head to dissolve the dried ink trapped inside. This will dissolve the clog and allow your expensive ink to flow once again. Most will then print as new.

Thank you for using fixya

This could be an issue with the connectors to the chips on the cartridge, make sure the chips on the carteidges are clean then check the ones on the inside of the ink holder, POWER OFF before doing this as you could cause damage to the printer if powered on, lift the lid, wait for the rack to engage the centre then turn the power off at the wall.
Hope this helps
Paul

remove the rear cover that conceals your main pca. turn on your printer and check the cpu fan. if the fan is not rotating up to speed, this can cause your problem. you can purchase a similar fan at microcenter or you can search online for one. shouldn't cost you more than $10.00. you can purchase it direct from HP the part number is (if they haven't changed the number) Q1271-60160

How did you do the factory reset?
Take out all cartridges and heads then unplug for 30 minutes?
Plug back in and reseat all removed items?
If so you probably have a bad head.
You can order them through HP or Staples.
The heads have a very short life of 10,000 pages.

My hp psc 750 will print from my computer, but I cannot make a copy. It keeps saying, "Scanne Failure. Turn off and on again." I have done this several times and it still will not make a copy.

You must replace BOTH ink cartridges to get a sucessful alignment

My Lexmark Z715 printer has always worked fine until this morning. I turned it on and the light blinked so I turned it off and then on again and the cartridge slamed one side of the pinter and then slamed the other side. I tried it several times and always the same. It would not stop in the middle so I could check it out. Does it need replacing?