Hi, My plain white macbook will not boot at all. I upgraded it from 10.6 to 10.8 several weeks ago and it has been working fine. Now, when I power it up, the screen turns white. No wheels spin, no dialogue, no nuthin' but white screen. The optical disk drive spins briefly at first then shuts down. The whole time there is a loud sound like a cooling fan running wide open or maybe the HDD. Whatever it is, it never stops. There the computer sits with a plain white screen, loud fan or disk drive (not optical drive after the first few seconds), and stays like that until I hold down the power button and shut if off. No keyboard commands are recognized. It won't go into recovery mode, or do anything using keyboard boot commands. I tried making a USB recovery flash drive by installing "Recovery Disk Assistant" on a similar MacBook with Mountain Lion OS, but the broken one doesn't seem to recognize the USB ports when I hold down cmd. R, or just R. I can't find instructions on how to make a bootable DVD using another Mountain Lion computer. Help Please!