Returning to previous slide, cannot advance forward

I have a project where there are multiple slides with multiple clickable elements that have states.  Additionally I have logic tied to these clickable elements and states.  For example:

I have created a variable called "next" that at the beginning of all slides is set to false when the timeline begins.  This variable needs to be set to true in order to proceed to the next slide (the click the next button to proceed trigger has a condition that states "NEXT" must be true in order for the user to advance.  Three boxes once clicked are taken to a state "greencheck" (a green check appears to symbolize the reading of the pop up that occurs once the box is clicked).  I have an adjust variable trigger tied to the boxes so that once all three objects states are "greencheck" a variable "next" is adjusted to true.  This process works fine, but once a user is able to proceed to thenext slide and wants to re-visit the slide previous, the user cannot advance once he re-visits the first slide.  I know this can be resolved by having every slide reset to its initial state, but the project owner wants to see if we can avoid doing this because of end users who may complain. 

Any ideas?  I can upload project potentially if necessary or send screenshot (may have to do this as I work for a large public company).