Hi Noah,
You stated ". . . it takes me straight to the bios/uefi " so you are already there. If still puzzled download the manual:
https://www.asus.com/supportonly/Q551LN/HelpDesk_Manual
Another thought. How did you clone your grandma's HDD to the SSD? This is very important. The easiest with the Samsung Evo is to just use their utility:
https://www.samsung.com/semiconductor/minisite/ssd/download/tools/
Look for "Consumers' Data Migration Software v4.0
You might also download the instructions for it.
You also say you have Windows preinstalled. . . where? On her old drive and it boots fine?
If that is the case then Samsung’s “Data Migration Software v4.0” will solve all your problem.
Let us know how it goes.