djbadeaux

A couple months ago, my 2007 SL550 wouldn't start and I replaced the convenience battery. The red battery light never turned off, and the service tech said it would turn off after a few starts otherwise he would have to run diagnostics. I've been out of town with the car and it never turned off. Also the convenience functions wouldn't be available for 10 mins each time it hadn't been driven in a while. I recently returned to the dealership to get my oil changed and to check the red battery light. I was charged $155 to plug in for a short test and was told I needed a front passenger SAM for an additional $797. I drove home from the dealership with no problems but the car was completely dead the next time I went to drive two three days later. I'm going to check my rear battery and key fob battery tomorrow. Would those issues be too coincidental? And how hard is it to replace the SAM? Since only the dealership can program it in my area, I found one on ebay from a donor car with 23,000 miles, my vehicle only has 45,000 miles, will it need to be programmed or will it just replace the old one?