XPS L502X cannot access BIOS

Hello Marek,

Tapping immediately after the Dell logo appears, should take you to One Time Boot Menu and to BIOS Setup. If the operating system logo appears, wait until you see the Windows desktop, and then shut down the computer and try again. If that does not work, please let me know if this is the first time you are try to load the BIOS Setup after the motherboard replacement. However, there are few steps that can be tried:

1. Releasing the flea power of the system.
   Disconnect all the peripherals from the computer including the battery and the ac adapter and release the flea power by pressing and holding the power button for 5 to 10 seconds and check.
2. Try accessing Advanced Boot Menu by tapping F8 and check if that works. 
3. Also try connecting an USB keyboard (if available) and check if you are able to access BIOS by tapping F2 using the external keyboard. This would prove the functionality of the keyboard. 

Please try the steps and write back with results. 

I purchased a Dell XPS W/ Win 7 64 bit  a little over a year ago and have tried all the suggestions listed to access the BIOS. I am unsuccessful 98% of the time. When is DELL going to step up to the plate and address and fix this problem?