I have a mid-07 Santa Rosa MBP. When I turn it on, nothing comes on the screen (not even backlight), but I'll hear the startup chime and 2 seconds later, it reboots and does the same thing. Here is what I have tried: 1. Reset SMU 2. Reset PRAM 3. Replacing HD 4. Replacing PRAM/CMOS battery 5. Tried booting off DVD (but it reboots too fast after the chime) Any suggestions? Thank you.