That is grim news but thank you for notifying me. I will continue to water it for another month or so before I give up completely and start from scratch on a new tree.
"Powdery mildew" looks to me at a glance. But the trunk looks firm, rather than mushy ... so is it dead? If I were you I'd ask around a bit more before I'd start watering it. It could be that excess water was the problem in the first place. Just guessing. It is a common mistake to think that ficus needs lots of water and frequently. Being a tropical plant must be the reason for the misconception but the ficus should be rather dry between watering. I hope that I haven't confused you even more than you were.