This is an old repair I did a while ago and posted on thinkpads forums. Reposting here to put it all under one roof. We have quite a few IBM Thinkpads X31 in the family. They are built like a tank and work well enough to keep using them despite 2003-2004 datecodes. One day two of them started exhibiting identical symptoms- they would just refuse to turn on. No lights, fans or other signs of life. Luckily I stumbled on a schematic on the web, so that was a good starting point.