Hi i got this lombard 400mhz from a friend, but uit's not turning on. He told me that he took it to an apple store and they told him to replace the logic board which he did but it still woul'dnt turn on. I put the old logic board back in it and it did'nt want to start up "it was late so i went to sleep but forgot to diskonect it" in the morning i got it to boot up in os X but it crashed after a feew minutes. I realized that the fan by the modem is not working.

What could i do ? he also told me it would boot once in a while and not boot at all after that....

It seems to be a frequent problem talked on this board. I found some stuff that i'll try but any other help would be good thatnks.
ps. I'm new so go easy on me