When we did, found it was a 486 machine where the
battery backed CMOS ram
was (had been) baked up by an external battery plugged into the
board. This had been stuck to the back panel of the box. It had
exploded! Possibly connected to the board backwards? The force of the
Most likely it had tried to recharage a non-rechargeable battery. Lithium
cells in particular will explode quite violently if you try to recharge
them...
Of course a look at the schematics would have told you whether the system
tried to recharge the battery, but have you ever tried to get schematics
to a PC? But that's another rant...
-tony