2002 BMW 745 Transmission fail safe

My car was down shifting into 1st hard when the car was stopped rapidly from a higher speed. Now the car is giving me warning messages like ABA, Transmission fails safe with only 5 and 6 speeds, the car has lost all power for a minute and then rebooted itself, While driving on the highway it has caused a hard bump in the tranny, warning lights after as above etc. We downloaded the transmission module software and it has helped a little the downshifting but the other issues no, one dealer says it is the mechatronics in the transmission which is around $3400 another says new tranny needed, another says there are some pins in the rear which need checking, Any body got an idea?

Mark