The green "Register Now or View Appointment Details" button on your mba.com account is certainly not the most intuitive way to get your exam started (within 30 minutes of your exam's start time), but it works.
Step 1:Step 2:Step 3:By the way, I can confirm that I was able to use a wireless mouse during my GMAT Online without any issue.
Lastly, be persistent: my first attempt at the GMAT Online was cancelled due to my "looking off screen" before the test even started, my scheduled retake (which took 20 days) was 50 minutes late to start and glitched in the middle of the IR section, and my physical whiteboard retake required 3 retries before my exam finally loaded (according to Pearson Vue's error message, it was an internet connection issue, but my internet signal appeared to remain strong the entire time).
BE WILLING TO STARE AT YOURSELF ON SCREEN (OR USE MY TRICK OF SIMPLY CLOSING YOUR EYES!) FOR UP TO AN HOUR OR MORE WHILE WAITING FOR THE TEST TO LOAD, and to have to run OnVue / take a headshot / take photos of your ID and testing room all over again.
Also, beware of having anything on the walls behind you that resembles a human face when taking your headshot:
On my third and final try, I switched to a 5G internet signal instead of my normal (more stable) 4G connection, and voila, it worked.
Yes, I'm aware that my order number / registration ID are on the last picture, but I already took the test, so whatever.
Good luck to everyone on this test. I'm happy to be done with it.