Navigating to/from menu slide; Show Next BTN after all menu items are selected

[RayLan]

I have a main slide 3 menu buttons that link out to different slides. After they are done on one of the slides, they are to return automatically to the main slide to pick a new one. Thanks to Paul Wilson, I was able to disable audio on the main slide (on return). But I couldn't get the slide/button visit tracking conditional actions to work properly. Please provide steps to accomplish the following.
When all 3 menu buttons on main have been clicked, show the next button.
Note:
I am not using the State View option. I am going from one menu slide and branching out to another slide and then returning to the menu slide.

[Lilybiri]

Hide the Next button in Output.

Create 3 user variables v_1, v_2, v_3, Booleans with the default value of 0. I would use shared actions from my shared actions library, which would need another variable v_counter, to make it flexible to be used for any amount of menu items. But you can prefer duplicate advanced actions.  It may be easier to understand, will explain that 

Use the Success event of the Back button to return to the menu slide to trigger an advanced action:

• Assign v_1 with 1
• Jump to menu slide

Duplicate that action for the two other buttons, and change the variable in the duplicat.

Use the On Enter event of the menu slide to trigger another action:

IF v_1 is equal to 1  AND

    v_2 is equal to 1 AND

     v_3 is equal to 1

Show Bt_Next

ELSE

      Continue

Beware: the menu buttons need a pausing point. It is not really necessary for the Next button to have a pausing point, but if it has one it needs to be at the same frame or a later frame than the menu buttons. 

[Paul Wilson CTDP]

In this video, I show you how to build a lesson menu slide with a hidden quiz button in Adobe Captivate. Learners will arrive on the menu slide and see buttons that take them to each lesson in the project. Only once they have completed all the lessons will they be able to complete the quiz. This can be done with an easy method provided by Adobe by labelling your slide, objects and grouping your lessons into groups, but students from my recent class wanted to see how this would be built using variables and advanced actions (challenge accepted):

https://youtu.be/JYFvMHMaqec