Bought a refurbished Inspiron 5570 last month. It's been working fine until now. Today when I tried to start, it would run diagnostics and say no problem detected. After diagnostics, it says "No bootable devices found". The only option in the screen is Shutdown. In BIOS, it does detect primary HDD. Boot sequence only has UEFI option. Tried to restore default setting in BIOS without any luck. Tried to disable "secure boot" as per other thread but no luck. Can someone help?