The answer to 'my duct cleaning won't turn on' is that there could be several common causes, such as a tripped circuit breaker, a faulty switch or control board, or a problem with the motor or power supply. The symptoms may include the duct cleaning system not powering on at all, or making strange noises when attempting to start.
For DIY troubleshooting, you can check the circuit breaker and reset it if needed. You can also inspect the power switch and wiring for any visible damage or loose connections. However, if the issue persists or you're not comfortable working with electrical components, it's best to call a professional HVAC technician to diagnose and repair the problem.