I have an inspiron 6400 that is return to me by a friend just after clean up and maintainence. There is a problem occurs. The ON/OFF switch is not workable but the LED for capital letters, lock bluetooth,..., etc light up during start up. When start up, I need to unplug and then plug in the battery to start and boot it up. This has to be done when the powerr cord is unplug. It will not start up if the power cord is plugged in during the process. I have save many data and install many software into it. I wish this problem can be solved. I was told that there are no any mistakes done during the cleaning process, and I believe in it. Thank you sir/madam.