So my oem Exide+ battery was dead and my attempts to recharge it still only shows 12.4V on my meter. Also the circular indicator on the battery is indicating a black 'need charging' status instead of the green indication. Time for a new battery?
As a point of information, desulfating only has a chance of being effective if the the condition is not progressed too far. Basically, it sets up a resonance that is supposed to break the sulfur deposits loose from the plates which it is insulating.