The answer to 'mini split not turning on' is that there are several common causes, including a tripped circuit breaker, issues with the outdoor unit, problems with the refrigerant, or a faulty thermostat or control board. Symptoms may include the indoor unit not blowing air or the outdoor unit not running at all.
If the circuit breaker has tripped, you can try resetting it. But if the issue persists or you notice other problems, it's best to call in a professional HVAC technician to diagnose and repair the system. They can check the electrical connections, refrigerant levels, and other critical components to identify and fix the root cause.