Hi,
Few things may cause 3F0 error. Please try one by one:
- Bad hard drive or partition structure: erase the entire hard drive then use HP recovery discs to reinstall of the OS and all partitions.
- Bad hard drive data cable that connects it to the motherboard: replace/reseat the cable
- Bad SATA controller on the motherboard: replace the motherboard or laptop.
In your case, most likely is #2 above (because you replaced something which may cause loosing the cable).
Regards.