To get to the inside of the printer, you have to take off the scan plate. It is connected to the body of the printer with hinges and screws.

Open the scan plate and you will find the spot to replace the ink. Here you will see the inside of the printer. In the right front corner you can find the blue stick. Twist it to remove it from its gully.

Now, the scan plate can be opened completely.

Search for screws, one in both corners and unscrew them.

After taking out the screws, the valve can be taken off by sliding the part to the right.