I need to make a Genius appt to fix my iPhone because it is disabled but I can't find my serial number becuase I can't get my sim card tray opened. What to do since making an appt requires 2 stage verification and I can't get a text message either.

You can always call Apple @ 1-800-My-Apple in the US. If you are not in the US then you can ➔  Contact Apple for support and service including international calling numbers.

Furthermore, you do not actually need to make a Genius appointment for a disabled iPhone. You can reset the passcode by connecting your disabled iPhone to a computer (Mac or Windows with latest version of iTunes).

You can reset your passcode by following the instructions in this article by Apple ➔ How to reset your passcode on a disabled iPhone. You will need a computer for this task and all your data on your iPhone will be wiped clean in the process.

Axel F.