The engine in my Mazda is not starting. I am not sure if the battery is dead or it is something else.
If your engine is cranking over at a normal speed but not starting, your battery would likely not be the cause of the no start condition. If your car is not cranking at all, then yes, a battery with low voltage could be the cause. In your Mazda’s particular case, the ignition switch needs at least 10.5 volts to crank. If the voltage falls to lets say 10.4, it wont crank at all. That sometimes throws people off because the windows will work, the lights will too, and even the radio. A bad starter can also cause a similar condition to a battery with low voltage. Testing your battery, and testing your starting system is where I would start. A technician should be able to check for proper battery voltage, perform a load test on the battery and verify proper starting system operation.