There are many problems with the RS batteries and mainly the charger. I've noticed with my charger that while you think all the batteries are charged when it turns green, that actually only 2 or 3 of them did while the other ones never had a good solid connection to charge.

It sounds to me like this might be your case. When batteries are placed in series only one current can flow through them and the entire circuit; this will be limited by the weakest battery. I believe that at least one of your batteries didn't charge and probably had a small remaining charge--enough to slightly power the lights and make the steering attempt to turn.

If you have another charger, I would use that. If you have a multimeter, you could check each of the batteries. At a full charge, they should be around 1.3V. That charger definitely has many problems though.