Battery

I had a couple of very old laptops returned to me yesterday.  One of them was absolutely fine once I plugged in the power supply.  The other one was very dead. I took out the hard disc, which was readable with no errors. I put it back, and still there was no sign of life.  Google suggested checking the CMOS battery.  That's it, the orange object in the thumbnail.  It was deep in the innards of the circuit boards, and needed even more dismantling to get it out.  By this point, I decided that the laptop could just stay dead - it's over 10 years old, so not worth having more time spent on it.