The HP 550 Laptop Lost The Option Of BIOS, There Is No Menu

Indeed, the HP 550 laptop lost the option of BIOS, there is no menu where you can reset the data of the day, date and time as it loses this data, and each time you turn, you have to reconfigure it again, but since the option to display Windows 7 and not from the Bios. Change the RTC battery but remains the same. On the internet recorded this problem in different brands since 2004 and perhaps before, and I am confused by the amount of information given from the RTC change to change the motherboard, it may be a bug in it.
In the technical manual of the device appears as an option F10 to enter the Bios, but in my case, F10 does nothing more than what I press repeatedly.
With the menu option F2 to enter checking, among other things, memory, and hhdd, and tell him that in these menus is an option to configure the BIOS, but color appears paler, grayish, faded, discolored, and displayed on the screen, below, required to push F10, but does not occur at all. That’s how the BIOS option deleted from the system.
I inform you that to change the RTC had to completely disassemble the HP.
I was informed that warmed a little more than time ago, and change the thermal paste, you clean the vent, and opened with the drill as 120 holes with the drill below the apparatus, where the video chip is going to to breathe a little better. It was a preventive maintenance.
But my headache is in the Bios.
Please friends, I ask if any of you have encountered this problem in the HP 550, or similar, and could fix the problem, give me a help, because I’m in a dead end, and I think change the motherboard would be far too expensive.
Thanks in advance, and good luck to you.