Before ignition, the gas boiler burner needs to go through two stages: the preparation stage and the pre-purge stage. After the first two stages are completed through self-inspection, it can enter the ignition stage and ignite normally. What's the matter with the gas boiler not igniting?

1. The gas pressure is too low and the burner cannot be started;

2. The gas pressure is too high and does not meet the pressure required for the burner to start;

3. The burner is damaged and cannot be started;

4. The gas boiler lacks water, and the boiler does not start due to interlocking reasons;

5. The gas boiler is overheated, and the boiler does not start due to interlocking reasons;

6. The gas boiler is overpressured, and the boiler does not start due to interlocking reasons;

7. The circulating water pump is damaged, and the boiler does not start due to interlocking reasons;