HP DeskJet 842C

(From HP)

Reset the product.
Press the Power button ( ) to turn the product off.
Press the Power button ( ) to turn the product on.
If the lights continue to blink, Press the Power button ( ) to turn the product off again.
Unplug the power cord and USB cable from the product.
Plug the power cord and USB cable into the product.
Press the Power button ( ) to turn the product on.
If the problem persists, service the product.