Hi Nevin,
Please check Voltage at the cable that sits on the starter pin. Are there 12v if u press the button?
2nd pls pull the starter button cable off the starte and bridge from the positiv (big red cable on starter) to the switch pin.
If this is not working und magnet switch inside is broken.
In the repairmanuel u can see how to repair your starter
Other things u can check:
Is the short cable ok (from the top part of starter to body)
Try to hit it softly with a hammer while you push the putton.
I think best way to fix it is taking it apart or maybe better, ba a new, gearbox starter. Its not that expensive and works realy well. Starts easier cause of more rpm