You don't have anything vested at all after 4 years that you could exercise now? That seems unusual to me.

Sounds like equity in this company is really not worth that much because the company has yet to find a viable foothold after 4 years. If no investor will pay a reasonable amount for the equity, why do you believe it is worth anything? The ICO seems like a move out of desperation.

My advice would be to look for another opportunity while you're still gainfully employed. You may get into another opportunity with true growth potential.