If you see the POST error in the picture on your IBM Thinkpad 600X's screen, your BIOS battery is probably dead. BIOS batteries for Thinkpad 600Xs go for $40.00 online. However, the actual battery is simply a common lithium watch battery with a special (expensive) connector. I will show you how to carefully remove the connector from your dead battery and attach it a new watch battery purchased for $5.00 at Radioshack.
Parts and tools:
1x dead Thinkpad BIOS battery 1x CR2025 watch battery 1x Roll of packing tape 1x Sharp knife 1x Needle-nose pliers