How di I reset the ink counter on a canon mp620?

I found this at fixyourownprinter.com. Seems it works on most mp models and may work on your 620.

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 Power 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 Alarm and Power LEDs light
alternately, Alarm in orange and Power in green, starting with Alarm LED.)
4) When the Power LED lights in green, press the Resume/Cancel button the specified number of time(s) according to the function listed in the table below. (Each time the Resume/Cancel button is pressed, the Alarm and
Power LEDs light alternately, Alarm in orange and Power in green, starting with Alarm LED.) [hth: I believe the power button has to be pressed once more after cycling the alarm button to complete the action. The power/resume-cancel button LEDs toggle to help you count.]

Time(s) LED indication Function Remarks
0 times Green (Power) Power off When the print head is not installed, the
carriage returns and locks in the home position capped.
1 time Orange (Alarm) Service test print See 3-4. Verification Items, (1) Service test print.
2 times Green (Power) EEPROM information print
See 3-4. Verification Items, (2) EEPROM information print.
3 times Orange (Alarm) EEPROM initialization [hth: does not re-initialize Waste ink counter]
>>>> 4 times Green (Power) Waste ink counter resetting
5 times Orange (Alarm) Destination settings [hth: not applicable]
6 times Green (Power) Print head deep cleaning (Cleaning of both black and color)
[hth: 7-10 not applicable]
11 to 13 times Orange, Green, Orange (Alarm, Power, Alarm) Return to the menu selection
14 not used in servicing
15 Orange (alarm) return to the menu selection,.

Note: If the Resume/Cancel button is pressed 16 or more times, the Alarm or Power LED lights steadily without
any changes.