I would like to convert my Windows factory recovery discs, which consists of 2 DVDs, into a single bootable USB. I have tried formatting both USBs as either NTFS or FAT32, creating a single partition and marking it as bootable, then copying the contents of disc 1 then disc 2 (in that order) to the partition. No files from disc 2 overwrite the contents of disc 1, except autorun.inf, which I dont think matters for booting. Trying to boot the USB results in a blinking cursor on a black screen, booting from the discs works fine but it's just too slow. And discs are too prone to scratches, and yet another physical item I have to keep with we, as well as a USB DVD drive. The integrity of the ISOs the discs are burned from/copied from isnt in question, I've individually checksummed the files from the ISOs against the files on disc/USB, everything matched. And the ISOs themselves are checksummed, with a 2nd copy of each disc having been uploaded to Dropbox.
I've also tried mounting each ISO on my Zalman, I just get the blinking cursor. I've also tried mounting the ISOs in DriveDroid (Android app), connecting to PC via USB, but my BIOS either doesnt recognize it as bootable, or does see it as bootable but fails to actually boot it (same blinking cursor as before).