This screams "we need a lawyer". Especially since the sales are so new and, I am certain, one of the reasons you all purchased is the low $500 a month property maintenance fee that the seller (now self appointed HOA property manager) told you about. The bait & switch stinks of fraud.

In the interim, if I were an owner I would call a meeting of the other two owners and make a collective agreement that the monthly condo fees will be paid after the group can vote in a new HOA manager (4 months from the last sale) so he can not enrich himself in the interim.