You will get a bit of arcing on a link when you plug it in anyway (unless you have a 'pre-charge' link) but I would be surprised if that alone would be enough to reduce the connector to a point where it is not making good contact. Possibly just a duff connector, so worth making a new one to try.

Re: the cradle, it looks fine. As long as it prevents the robot's wheels from touching the ground and it is stable (i.e. give the robot a shake and it doesn't fall off) then it's good.