MBP Can't stay on - not the battery or HD

My 15" MacBookPro, OSX 10.5.8, 2.2GHz Intel Core 2 Duo, 4GB recently had a new battery installed. Prior to the new battery, it would sometimes turn off with a little "click" noise (not to be confused with shutdown, like someone "pulled the plug").

The Apple Store came to the conclusion that it was not the logic board, but the HardDrive. They installed a new HD, rebooted the OS and gave it back to me in top shape. Or so it seemed.

This sporadic "turn off" has turned into a regular occurrence. It might turn off as I am writing this, and my browser is the only thing I am running. If I try to turn it back on, it often will make the "click" noise and turn off before it has finished making the "Mac" sound. This can go on for 5 or 6 tries before I finally make it to my desktop.

If I put the MBP to sleep over night or while I am at work, it has turned itself off by the time I get back, and the routine starts all over again.

Any tips, suggestions or ideas besides taking it back to Apple?

Any tips, suggestions or ideas besides taking it back to Apple?

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This is one of those things that you'll be pulling your hair out trying to resolve. Take it back to Apple. Since you already have a record of repair and replacement with them, let them figure out the next step. I suspect they'll probably say it's a bad power supply, which means a new logic board.

Try a PMU reset. And apple should give you a refund on the drive seeing how that is not the issue.