I feel for you too. It wasn't a startup and the job was local, but I took a salary drop and swapped a cosy-but-unrewarding role with a global corporate to join a 40-strong SaaS development company that wanted someone to come in and sort out their internal and customer support infrastructure - they had no strategy, procedures or hierarchy and were constantly firefighting - shuffling resources between projects according to which customer complained the loudest.
It became clear very quickly that the two founders who brought me in wouldn't embrace any change that didn't come from them, and they had a total fear of empowering anyone else to make executive decisions - even about their own team members; I constantly found my guys being assigned to firefighting for other teams without my knowledge, so workload planning and scheduling knowledge sharing periods was impossible - we had information silos all over the place and if someone went on vacation they would often be called or emailed frequently because they were the only ones who knew about a specific part of a project or system. I wasn't allowed to attend support review meetings with the customers - the Directors went alone and told me what had been agreed, and they constantly dealt directly with one of my guys (the company 'guru'), assigning him work and making it impossible for me to grab his time so he could share his skills with the rest of the team - I highlighted it as a serious business risk that this guy was the only person who knew some of the tricks with some of our internal and customer infrastructures, and that he wasn't encouraged to document or share his knowledge, but they dismissed my concerns.
When we had that Friday afternoon talk after 9 months of trying to bring in some best practices and semblance of organisation, I left the office for the last time with a sense of great relief that I was out of the clusterfuck.
It only took me a few weeks to find a much better role and I hope things work out for you too.
Edit: Looking back at what I wrote, it might be that the OPs circumstances just offered the opportunity for a bit of a personal rant, which was not the intention. My main point was based on the fact (not explained at all by me in my post) that when I met the two Directors (twice), prior to joining, the setup and opportunity for me looked very positive, and I was convinced I was going to be empowered to fulfil the role. Things turned out very differently, and I clearly did not fit in with the company culture the founders wanted to both leave and stick with simultaneously (it was their comfort zone, and although they knew is was not the best was to run a business, they ultimately couldn't leave it). Moral: Shit happens, despite due dilligence, but that doesn't make it right.