"I tried a few time to power OFF/power ON, or to do a cold reset (Shift+Break+RESET) but the result didn't change: "
That doesn't always do the trick, if it's crashed it will ignore the keyboard. Meanwhile the "memory power" NiCd keeps the corrupt zombie RAM in its corrupted state. The goal is to clear the RAM state. Sometimes you need to shut off memory power switch on the bottom of the unit and let the whole unit drain of power (no internal batteries, no DC power hooked up). After you do this don't forget to turn the memory power switch back on. Since it only took a months to corrupt your RAM I would also be suspicious of the internal NiCd. If you haven't replaced it chances are it's 20 some years old and needs replaced. http://bitchin100.com/wiki/index.php?title=Recovering_an_Unresponsive_Laptop -- John.
