This link to the ipd site may answer your questions about the 25amp fuse.
It's a good idea to replace the factory fuse holder with one that is
waterproof. They can usually be found at boating supply shops.
http://www.ipdusa.com/Volvo-200/Electrical/Watertight-Fuse-Holder/p-69-257-162/
As the others have posted, the fuses in 240 Volvos are more often than not
the cause of no-starts. To fix it right, disconnect the battery, pull the
fuse box, clean any corrosion on the wires and contacts, fix any potential
water leaks and replace all the fuses with new.
Good luck with it, and let us know what it was after you fix it.
Don
