As PCs age you enounter "The Dead PC" from time to time. Long ago I even owned a PC repair shop and learned a lot from the experience. But fast forward to today.
While I know a bit about PC design something of a mystery to me is why folk have been pushing back on a common cheap thing to try on dead machines. Pop in a new CMOS battery.
I could go on why this can cause a PC to hang but here if it's the usual CR2032 we buy these in bulk for the office at 25 cents USD each. It's a dollar part most everywhere here.
Why do people push back on this thing to try? Do they really want to incur a shop counter charge to test the 25 cent part? I think they don't get it that past a few years these can deplete and cause a machine to hang on power up.
And yes, we add a 1/2 hour diagnostic fee to the bill if they want the battery tested. That's 75 bucks USD. High but they did ask for that.