Yes, the starter itself can be ' shorted' just like American cars...
but cleaning the posts may leave the other end of the cable still not transmitting electricity...AND on our old cars you can get enough corrosion under the rubber near the battery to make a difference... might just put new cables with cleaned attachment points on the car and then go from there...
Are you getting NO noise.. no clicking or anything ?
Do your inside lights dim when you put the key to ' start' ?
Open your door to turn on the inside lights...