Lenovo ThinkPad T400s was a laptop introduced by IBM for corporate and commercial use. The T400s was released along with the T500 in July of 2008. Similar models include the 400, 410, 420, 510, and other models in the ThinkPad T series.
Because your laptop is old, replacing the back-up battery will insure that your clock will continue to function. See the link to our replacement guide to help you replace the back-up battery.
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