The manager of my current team came up with some complex way of solving a problem that we're facing as a business. He implemented a proof of concept and showed

The manager of my current team came up with some complex way of solving a problem that we're facing as a business. He implemented a proof of concept and showed the business without involving anyone else in the dev team at all. Now the business wants to roll with this "solution" to a key part of our software we've been desperate to refactor with foresight of incoming requirements. Instead we're ploughing forward, saving refactoring for later to implement this proof of concept. No design work is to be done - only implementation because we're on a tight fictional deadline. He's throwing more developers on it to "help" and even micromanaging the implementation. The same manager expressed displeasure that he wasn't involved in discussions with the business about a new project that rose whilst he was away on holiday. Follow this guide at your peril.