Glad I could help. If you have other questions, feel free to ask me again. I am always happy when a dead BIOS (EFI) becomes alive again. Your job is to 'unbrick' machines and I am glad when I can help.
Usb port memory stick is inserted into the FAT (or FAT32), in which the file is N53SV.BIN. Power on the depressed CTRL + home, the status LED blinks a few times as if he read something, then restet and nothing happens. It takes several seconds. Maybe the file name should be different? Maybe a combination of keys?