Laptop will not turn on after replasing bios battery.

Hi fover,

So let me get this straight; your goal was to replace the CMOS (BIOS) coin cell battery, which you did successfully, right?

So, why did you remove the CPU?

Generally the CMOS battery will only affect the BIOS' ability to retain information when disconnected from AC power, and most systems will generally run even with a dead battery as long as you don't mind reentering BIOS settings every time you plug it in. So I would discount the battery replacement as having anything to do with your current issue.

The CPU R&R, on the other hand, has all the potential in the world for disaster. That's where I'd be focusing my attention as the source of the problem. It's all too easy to damage those delicate pins in the socket when the CPU has been removed, so that's the first place to look. Pull the processor out again and take a magnifying glass and a bright light and look at the pins carefully from several angles; you will see a discontinuity in the pattern of the pins if any are bent or damaged. If so, it's sometimes possible to straighten them with a pair of fine tip tweezers, but be very careful not to mess up the surrounding pins when working on one.

Of course, you'll want to check any other plugs that were removed in the course of your repair and verify that everything is plugged back in correctly and securely.

Good luck; let us know what happens!