Hi,
Start by replacing the CMOS battery of your laptop first with a new one. If this will not work remove the HDD off the laptop then boot it up and see if it would still load back into BIOS because if it will not that means the HDD is faulty. Just to make sure that it's the HDD, put it back in and boot it up and again if it gets stuck in BIOS you got your suspect already. But if without the HDD and the laptop gets stuck into BIOS that means it's the motherboard that is faulty.