The LLC Agreement will likely govern how and where the claims you may have can manifest themselves. It sounds like - since you are locked out - quick action may be needed. You should consult with an attorney as soon as possible. I'd be happy to discuss the matter with you.
You likely face an uphill battle since you did in fact sign. That said, you may be able to use the non deposit and/or a theory of duress to try to get out of it. I'd be happy to discuss it further with you,
If you were not provided with any new consideration when you signed the new non-compete, it may be unenforceable under Washington law. I would suggest you consult with an attorney to potentially have that attorney contact your previous employer and explain your position.