IANAL, but I know that if you and they signed on the dotted line, apart from the ethics, you have legal rights. Probably fewer in the US than other places, but some protection.
If nothing was signed, then I don't think you "officially joined" as COO. From their perspective, it might simply be more of an episode of serious miscommunication, than any untoward behavior on their part.
What precisely does that mean?
IANAL, but I know that if you and they signed on the dotted line, apart from the ethics, you have legal rights. Probably fewer in the US than other places, but some protection.
If nothing was signed, then I don't think you "officially joined" as COO. From their perspective, it might simply be more of an episode of serious miscommunication, than any untoward behavior on their part.