@jhsworl you're not telling us if it does this on AC power as well as battery power. The "“plugged in, not charging”" could be a battery issue but could also be a issue with the charging circuitry on the board, Double check your DC in jack to ensure it does not have any loose connections.
Download the Hardware Maintenance Manual [https://thinkpads.com/support/hmm/hmm_pdf/t440p_hmm_en_sp40a25467_01.pdf|from here] It will help you to work on your computer. If you get stuck or need further help, you can always post images of where you are or what you may have questions about, with your Question. Use this guide for that.
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