The answer to 'boiler not turning on' is that there are several common causes, including a faulty thermostat, low water levels, or issues with the pilot light or ignition system. Symptoms may include the boiler not heating up, strange noises, or the pilot light going out.
For simple issues like a tripped circuit breaker or pilot light problems, you may be able to troubleshoot and fix the issue yourself. However, for more complex problems with the boiler's internal components, it's best to call in a professional HVAC technician to diagnose and repair the issue properly and safely.