"Start legal action" may not be possible at all. If it is possible, there's a range of possibilities in between "lawsuit" and "do nothing." If the company has h

"Start legal action" may not be possible at all. If it is possible, there's a range of possibilities in between "lawsuit" and "do nothing." If the company has hard-to-argue with legal duty to pay you then a letter from a lawyer might suffice. Step 1: talk to startup, say "this is not cool" and see if you can get them to cough up some money. Step 2: If that doesn't work find a labor lawyer and just asking them what they think. They'll probably be able to say "don't bother" or "I can write a letter for $X, but it probably won't work" etc. without you having to pay upfront. In parallel: assume it's a loss and find some work.