CMOS Battery
 

Lifetime event: I replaced the motherboard cmos battery in an ancient PC (2010) after it became troublesome and in the end wouldn't boot. That's a lifetime first. The fact that the bios lost date and time a week or so back was the clue. Apparently the advice is to replace them every 5 years but I am not made of money.
However, in addition to now booting, the whole machine seems sharper and more responsive somehow. So to those with old machines perhaps change the battery ?

Perhaps the effect of the battery failure was to restore the motherboard to factory settings.

Was it a battery type other than the typical CR2032?

No, it was a 2032. Amazed it lasted so long.

Maybe so. Seemed to hold settings more less. Wonder what else it affects.

Had an intermittent fault on an old Lenovo laptop which prevented it from booting up properly. The remedy, prescribed by YouTube, was to remove the battery pack AND the CMOS battery for 20 mins until all residual power had ebbed from the circuits, reassemble and away it would go.

Ah the days when removing the battery was simply pull back a couple of clips and to get to the innards undo a few screws. Now you need a combination crowbar, tin opener and acetylene torch and in all liklihood something will crack as you pry...