Is my controller ruined?

Have had this white wi-fi controller since Christmas and it's solely ever gotten like 4 months of use. For some time I feel I simply used common AA's however then made the change to these Energizer Rechargeables. Can't recall ever having to take them out however I figured I'd cost these two with the opposite two I’ve .

Opened up the again to search out this crusty movie on each side of the underside slot and a few seems prefer it made it behind the unfavorable steel piece. I put each totally charged batteries again in and received no energy to the controller. I really feel like this crust has one thing to do with it.

Is that this fixable or is my controller a misplaced trigger?