I have been refurbishing two of these laptops lately and, along with some Toshibas, have eofund that laptops of this vintage with NiMH CMOS batteries are susceptible to damage by corrosion.

Here are some photos to help describe the extent of the damage. Corrosion is often visible at the end of the CMOS battery wiring and also at the point of connection with the system board, even if the battery itself does not show any sign of leaking near the cells.

Another photo is of the LCD lid sensor. It's completely destroyed, and the spring inside has disintegrated.

I've also included photos are of the bottom of the case. Notice the triangular shape of discoloration. This was previously a sickly green color, and whatever paint was used here seemed to proliferate the corrosion. It's no longer green in the photo, as I have since treated it with vinegar and scraped it clean with a wire brush.

The PCG-Fxxx series laptops connect to the CMOS battery via a smaller daughter board, which also connects to the battery. Even if the main board is undamaged, if this daughter board fails, the system will no longer power on. This was the fate of one of my laptops.