hello toms hardware community. i have been searching and searching for an answer to fix my laptop. I have a HP DV4-1435DX and one day the laptop worked fine the next it wouldnt boot past the HP screen. At first i thought maybe hard drive died after replacing the hard drive and running the windows install i had the same issue. My uncle has PC service doctor and run a check my old hard drive was good, motherboard was good, but it said CMOS fail. after doing more digging my laptop will not detect any hard drive. In my diagnostic log i have error 03F0 Hard Disk Does Not Exist and 0502 which i cant find what that is. I think its my bios sata drivers because the laptop will not read any hard drives. when i try and run a windows 7 install when i get to select a drive it says ""No device drivers were found. Make sure that the installation media contains the correct drivers". So i can update my bios because i have no OS and my motherboard doesnt find any hard drive i tried to run Gparted Live and that didnt find any drive either. does anyone know what can i do. hp wants 250 to flash my bios and to me thats way to much laptop isnt worth that much and i feel it something i can do myself just dont have the right info. so if anyone knows anything please post