I need help with my canon pixma ip4000. When i press power button, printer make test or something like that (empty round) and stop. Red and yellow led are flashing. What to do with it ?

Be warned not to reset the counter too often, there will be ink build up in the
sponge and at some stage this will have to be replaced or cleaned, if you reset
more than once and do not replace or clean the pad there is a severe chance of
ink spillage onto the base of the printer, your desk and the
carpet. You have been warned

Service mode

1) With the printer power turned off, while pressing the Resume/Cancel button,
press and hold the Power button. (DO NOT release the buttons.
The LED lights in green to indicate that a function is selectable.) .

2) While holding the Power button, release the Resume/Cancel button. (DO NOT
release the Power button.) .

3) While holding the Power button, press the Resume/Cancel button 2 times, and
then release both the Power and Resume/Cancel buttons.
(Each time the Resume/Cancel button is pressed, the LED lights alternately in
orange and green, starting with orange.) .

4) When the LED lights in green, press the Resume/Cancel button 4 times. (Each
time the Resume/Cancel button is pressed, the LED lights
alternately in orange and green, starting with orange.) .

5) Press the Power button. The LED lights in green, and the reset is performed.
(When the operation completes, the printer returns to the
menu selection mode automatically.) .

6) Press the power button to exit service mode.

Note:- if you accidentally press the Resume/Cancel button more than 4 times in
step 4 then just press the Resume/Cancel button at least 10
times and the printer will be returned to step 4 automatically.

BTW the other functions that are available at step 4 are -
press 0 times = power off
press 1 time = Service Test Print
press 2 times = EEPROM information print
press 3 times = EEPROM initialisation
press 5 times = Destination settings (country information, do not play with
this)
press 6 times = Printhead Deep Cleaning
press 7,8 or 9 times = not used in servicing so do not play with these.
press 10 times or more = return to menu (step 4)