A lot of that saga is recorded on this on this thread if you search through. Basically one of the devs Joshua Yabut had what I would describe as a breakdown and posted a Tweet revealing a vulnerability in code he was responsible for, and encouraging ZEN to fall. Not quite sure on the timing of when he was kicked out, but from his Tweet it seems pretty clear to me he knew his days were numbered and the other devs wanted him out.

Other devs removed him, and brought in consultants to fix the vulnerability, which fortunately wasn't exploited and is now fully patched. I'd describe Joshua's behaviour as more "crazy" than "shady" because after all he didn't exploit the vulnerability for personal gain, but it really hurt ZEN price which had done great on opening on Bittrex, and we're really only recovering from that this last week.

I think that incident can continue to damper enthusiasm on ZEN, but with declining impact as time goes on.