It took me hours. Was I the first person this ever happened? Of course not! Many thanks to Apple community - Mac Users.
My MBP15 early 2008 wouldn't switch off when chosen to restart, after patching up. Hard shutting down worked.
Keyboard is not illuminating, but I know by heart where is which key, after decades of use. As a matter of fact, for the past few years, this machine was picking up dust on a bookshelf, as obsolete.
I cannot thank enough fellow Mac User from Barcelona, for pointing out this possibility, and another from Herceg Novi, for handing me a Pendrive, which made a meaningful OS X possible.
Investment in Mac / Apple has proven worth every penny, countless times, and again. I am thrilled!
After obtaining, from the same two users, confirmation regarding Apple Silicon being a game changer, I will get hands on one as well.
They seem pricy, but when I got this machine, it's pricetag was 2.500€, back in 2008. And it seems to work better then ever, with SSD and Catalina.
Cheers!