My lenovo Thinkpad L420 shutsdown few minutes after booting . I recently updated it to windows 10 because wifi drivers were not working when it was on windows 7. Now after update it boots perfectly and after a few moments it shutsdown, tho it doesnt shutdown if you didnt unlock the screen. then it stays on for all the time. i tried a lot of methods but none worked so far, A bit of help is required.