Could use some help. Have an old Dell Dimension D300 that is basically used as a word processor, etc. Son disconnected computer approx. three months ago. Battery went dead on the motherboard. Replaced the battery but the BIOS still will not power on. Fan works, CD Rom opens, etc. BIOS does not start up. What else (besides changing the battery) has to be done to get the computer running? Thanks for any help in this matter. Ralph