I have a ASUS F501U which was also stuck in BIOS (aptio Utility). Ended up being my HDD was loose after I was a little bit careless with it today. I was also surprised to see the HDD wasn't screwed in place......mine was held in with what looked like masking tape.
No apologies if this is a repeat response in another forum. I only figured out my RIDONKULOUSLY simple to fix problem after reading an off topic remark in one of the links above. I mean...I was about to try reinstalling the OS and/or play with the grub or one of the other myriad of other complex solutions presented.
TLDR: Stuck in BIOS with no boot options? Dropped your laptop today? Check if your HDD is seated correctly.