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?
nothing happens, just ctrl + home gives a response and starts flashing pendrive. The effect is independent of the file's contents. Even as the file is not present on the flash drive, it looks as if it was not appropriate file name.
Well I don't know if it matters but the filename for recovery is N53SV.bin, not N53SV.BIN (capital letters). You can make some copies of it and try different names at once. Be sure all the files are at root directory... Names: N53SV.bin, N53SV.BIN, N53SV.fd, N53SV.FD, N53SVAS.209, N53SVAS.bin, N53SVAS.BIN, N53SVAS.FD, N53SVAS.fd, N53S.bin, N53S.fd (suffix: .bin or .fd or original.....filname: some letters of the original one. It should be .bin and the first 5 letters here though.) Alternatively try to burn them on CD since the recovery should also work from CD.... I don't have tools atm to check for the recovery filenames, but I think there is only one...detected by andyP's mod tool...