Antique Mac laptop still works!
A week or so ago, I turned on my old (1994) Apple PowerBook 150 to see if there were any files on it that I had failed to transfer to my semi-old (2001) iMac. To my horror, I got the dreaded "sad Mac" icon, meaning that there was a fatal bootup error. Repeated attempts to start up failed as well, so I put the old thing away, fearing it was gone for good.
Today I tried to start it one last time before discarding it, and on the first attempt there was no response at all. Then I tried something different: I removed the battery (while it was still plugged in, of course) and hit the ON switch again. Eureka! I don't know why the presence of the battery might have affected it, but it has virtually no charge storage capacity any more in any case, so it's just taking up space. The bootup took longer than usual, but the Finder and applications worked just like new. There isn't much practical use for the PowerBook, because the only removable disk drive is for magnetic 3.5" diskettes, and none of the ports are compatible with USB or FireWire, so it's basically a curiosity, or perhaps a museum piece.
Try this color test humorsphere.com, to see how young your brain is. It took me a few attempts before I figured out what you were supposed to do, so perhaps my brain is aging faster than I thought.