CMOS backup battery replaced, my Presario M2000 still dead

I'm having exactly the similar problem with you guys here now... it all started last night when I was operating it, browsing here n there. As the 'low-battery' sign appeared, immediately I plugged the DC power jack in. But only seconds b4 I plugged the other end to the wall, everything on the screen disappeared just like that ...n no signs of life even after I replaced the CMOS backup battery (ML-1220) with a new one.
To tell you the truth, dizis the 2nd time I experienced such failure in 5 months. When I had it for the 1st time last September, I sent my Presario M2000 back to the dealer to have it repaired. He did say it was the MB n there was nothing he could do but replacing it with a new one. So I had to spend some Rp800,000- (Indonesian Rupiah), which was US$80- averagely, for a new MB.
I had to agree with him, since I know too little about hardwares.
So, pls tell me, how I should fix it... coz I couldn't afford to buy a new one. Thank's and GBU...