DELL 1545 heartache

My son's friend from school and my daughter both have Dell Inspiron 1545 laptops. Coincidentally, they both ended up having bad dc power plugs. I tried to desolder my daughter's plug off first without much luck and ended up snapping the little board. So, I went ahead and bought two of the power boards and installed them on both, while being careful and following all the rules. I have done things like this before, and I took my time and put them back just like they were. Now, they both only work on one piece of RAM. Yes, I was upgrading one of them, but have since gone back and tried the original RAM. Has anyone had this type of problem before or something similar?   I am at my wit's end.