Everything connected and the inverter won’t start? Is the inverter defective? Not necessarily.
Plus and minus swapped. This often happens when you swapped the plus and minus, e.g. when you used the same colored cable.
Check starting voltage. With many inverters there is a minimum voltage that must be reached so that the inverter can be switched on. These values are in the data sheet or in the operating instructions. Please be sure to check the voltage values, because too high a voltage can destroy the inverter.
The inverter is defective, in which case, in the event of a warranty claim, contact the manufacturer, or contact us if the device is ordered from us. You will often receive a replacement device or a new device.