How to bring back a very old and already dead PC?

I have an old (ca. 1998) Toshiba Windows PC with Windows 98, of course, but it has been long dead. I think it has something to do with an internal battery that was used to keep some things ticking when it was turned off, as it has been for over a decade ago after switching to a Windows XP machine, by now also replaced with my present one running Windows 7.

I need to do something with this old machine and would appreciate advice on who, or what kind of PC-care business, might be able to bring it back to life. Thanks.

Ex-Windows user (Win. 98, XP, 7); since mid-2017 using also macOS. Presently on Monterey 12.15 & sometimes running also Linux (Mint).

MacBook Pro circa mid-2015, 15" display, with 16GB 1600 GHz DDR3 RAM, 1 TB SSD, a Haswell architecture Intel CPU with 4 Cores and 8 Threads model i7-4870HQ @ 2.50GHz.
Intel Iris Pro GPU with Built-in Bus, VRAM 1.5 GB, Display 2880 x 1800 Retina, 24-Bit color.
macOS Monterey; browsers: Waterfox "Current", Vivaldi and (now and then) Chrome; security apps. Intego AV