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Which green light on your PIXMA printer is always On, please?
Can you turn the printer Off, still?
Unplug the printer. Leave it that way for at least 2 hours.
At the end of that time plug it in to the power again, and try it again. See if that rest and reset cures the problem - I hope so, though I am not certain it will. The printer might be permanently 'broken', by the sound of it.
Then your printer is 'broken', and out of warranty... it is a decision at this point, as to whether you wish to have it repaired, or to recycle it or dispose of it and buy another printer perhaps.
If I can help you in any way with that decision, let me know.
(* by 'broken', I mean that a printer that has ceased to respond to even the power button, has got a severe malfunction in its central control circuitry. It will not be repairable by you, by any simple measure, if you have already tried shutting it Off, and unplugging it from the power, for 2 hours or longer continuously.)