The blackscreen with F1, F2 option usually(which i've had recently with my sis laptop) comes or came from :
1. Previous undetected/error devices upon booting
a. Battery is reinserted which made the CMOS/BIOS reset on booting the system.
b. Faulty or loose cable, network/wireless card, RAM modules on slot/s.
c. Any hardware changes from laptop which the system is not recognized on booting.
(Note: My opinion is just base on my recent work on the laptop and your issue may vary)
Have you had any similar or familiar on these issues?