I forgot to mention the first time, I enabled passthrough on 2 cards at once. The second time, I tried one card at a time, and it worked(but I don't know whether to attribute that to the fresh install of the esxi, or the order of things)
I was able to get back the managment by removing the said cards, and booting. When I rebooted to add the cards back, the mangement connected in vsphere client...and all passthrough was again disabled.
trying another attempt.
yes, it worked...enabled passthrough on both devices, and rebooted...they both show up as available to passthrough.