I am having the same problem. I have charged it, checked the hard drive(it is seated properly), checked te ram(both slots seem to function properly) and reseated the battery.
When I turn on the computer (Dell Inspiron 1545), I see the Dell logo and prompts of F2 and F12. I have checked the Bios and all settings were set to default. All the diagnostics run say everything passed.
Problem is I still cannot get into Windows 7.
If anyone can help it would be greatly appreciated.