> very sad news:

>       ce, switched the machine on and ... nothing happened. all LEDs were lit

Do the LED's just turn on and stay on, or do they follow a sequence.  The
LED sequence indicates the hardware self-tests as they occur.  I have the
hardware manuals for that beast and if you can see a sequence, I can tell
you where the self-tests are failing.

Other than that, I would do some simple sanity testing, like measuring VCC
to make sure the Power supply is still good.  Did something short when
re-mounting the board??  Maybe try re-seating all the memory boards.  Also
I know that I had a bitch of a time installing the 040.  I had to put all
of my weight on it to get it to seat itself far enough in the socket.  If
you don't support the board properly when doing this, it's very easy to
crack it and break a trace on an internal layer, in which case you're SOL.
Or when applying that much pressure, you can bend a pin on the bottom of
the board and cause a short.  Try checking those.

Good Luck.

Dave