2002 BMW E46 IT Wagon just changed the battery from the original Bosch, now transmission error code and slippage? Could it be a fried sensor?

Hello Everyone,

My baby, 2002 BMW E46 325i Wagon (automatic) with over 250.000, miles on it is sick.  My original Bosch battery died last week and my husband purchased a quickie Wal-mart replacement battery same supposed thing :(, anyway I'm thinking it is not the same thing and neither is he. It was really cold following the battery install and I noticed the shifting was a bit rough, but blamed it on the cold weather. This past Friday it was in the 50's, and I was driving it and same rough shifting then the transmission error light came on and went into limp mode.  I pulled into a parking lot, parked it and turned off the car.  I waited there (while I called my Husband) for a few minutes then restarted it to try and get it to my Husband's office about 3 miles away. It was fussing and rpms going a bit high (no red lines) but I made it. After all of that here's my question: since this car is picky electronically, ( I recently plugged a stupid cheap I-pod adapter with blue tooth in the cigarette port and it fried my blower module! I proudly fixed that myself :) ) could it be that a module or sensor is messed up from the sub par battery? I have done the transmission reset. But not exactly sure if I did it correctly for this car.  I turned the key to accessory, held the gas to the floor for 30 seconds then turned it off, then restarted and drove it. It did not seem to help. What do you think?  I appreciate your input!