Help connecting an old phone to make a midi controller

Hi! I'm new in the Arduino world and I'm trying to build a midi controller but I'm having some issues. I'm following this video

and using the same code. the guy there uses an old phone keypad as one of the components. From my understanding most keypads are wired with a wire coming from each column and each line but the keypad that y got is wired different so when I connec only some of the keys work. So my question is how should I connect it to the Arduino (I'm using a mega) for it to work? Or should I change something in the code?

I'll leave a picture of the phone and the keypad I'm using where you can see how it's wired

And here is the part of the code regarding the keypad theMIDInator/readKeyPad.ino at master · SwitchAndLever/theMIDInator · GitHub

only some of the keys work

Notice that the upper left key is not connected at all - * or # key? Also the lower left key is only connected on one side - gotta have both sides connected to make it part of the matrix.

It looks too like there could be a short from a solder blob on the upper right switch. There might also be a short on the rightmost edge connection from excess solder.

Make a drawing with each switch in its relative position on the board. Include the edge connections and duplicate the physical layout in schematic form. Include the switch names on your schematic. When this is done you will be able to see how to connect the two unconnected switches so they're included in the matrix.

A 3x4 matrix may work or you might need to add an extra column or row for a switch which won't fit.