2019 Mazda 2 intermittently not starting (video attached). Has done it for as long as I can remember. I go week/months without the issue and then it crops up again.

We have tried using second fob and have changed batteries on both. Car battery voltage is absolutely fine. Any ideas ?

 

Ok so first you can't assume that the battery is absolutely fine unless you did a battery load test. I cant tell you in the hundreds of people that have stated that over the years to find out they have a bad battery. Voltage of the battery is not everything.

So with that in mind your battery should show min. 12.50 volts to do the test.

Because you joined this forum so fast and s[ped through the normal member information no one has any idea where in the world you live...so I can only state that if in the USA there are numerous parts stores and places like Firestone that will do a FREE battery load test for you.
Some auto parts chain will even do a basic ECU scan in at least one area of the ECU.

After that you then need to do a 3 point scan of the ECU.

Without you doing this anyone can guess so I will guess at the worst scenario given the year, you may have a BCM problem GUESS !!