|I'd think that your problem is caused by some change that you did.|
Might have a tech person or friend that knows a lot try to return bios settings to default or failsafe and then save them. It may be that some entry you made is not possible and that is why the F1 issue?
Dell usually has all the docs if you use your service code on their site.
Why did it take me over a year to phone in a problem to ATT?