Car won't/ struggle to start?

Had these before. But happened again today.

So basically, I didn't left anything on, no lights on, except I left my dash cam plugged in to the cigarette lighter socket. Then when I press the start button, it won't start. A few more attempts and it still doesn't work, so I get a jump start from a friend, then it worked fine.

Then I had my battery tested in ktec, they did a discharge test and they said its fine. Cars only 3 years old, so I presumed battery shouldn't be the problem right?


Today, when I pressed the start button( clutch down obviously) it turns 2 clicks then complete silence for 3-4 seconds, then click again and it had started.

Any ideas what can be the true cause?
 
If it's starting fine as soon as it's been jump started, it sounds like maybe the starter motor? If the battery is holding charge and it's been tested, then that's not the problem and the alternator is doing it's job by charging the battery.

That would be my guess to start with? Check the connection on the starter motor.