Wow...you're in a real pickle...I do believe you need to see the nav screen.. It is the display for the OBC...the display in the cluster belongs to the check control system...and although you can program the OBC to appear in the display...it cannot control/set/reset/start/stop any of its functions. All of that is done by the controls on the nav monitor (or MID if optioned).
Its been mentioned several times (about the owners manual & downloadable PDF versions of it)...but you haven't said anything as to if you have them. Get the instructions for emergency activation of the OBC CODE...perform it, then see if it brings the nav screen back or if you can see the prompts it gives you in the check control display (cluster display).
EDIT: you need to find the section below in your owners manual...but turn to the next page (or whatever page it refers you to) for emergency deactivation procedure: