You don't have to be good at soldering because all you need to do is re-flow the existing solder joints again. There is a coating on the PCB board that you may have to clean off first (just around the solder joint). My bad connection was actually the little blue rectangular capacitor next to the main 26 pin connector. My did the same repair to my friend 97 328is. If you look down at the board:
***************
* Blue connector *
* *************
****
**** blue rectangular capacitor
This capacitor is a line filter for the power to the board...this is why you get a on/off situation if you have a bad connection. As you can see I spend quite a bit of time researching this topic because the stealer want $600 for a recondition part and they have a back order of two months.
Good lucks