I received several new Cisco 2960x switches to configure and one of them would not boot up stating that the image failed digital signature verification. These switches have USB interfaces on the front and can be used for file transfer, however more modern USB flashdrives would not work for me. I had a few older USB flashdrives that worked, so hold on to your flashdrives!
From a working switch, copy the boot image to the USB flashdrive.
"copy flash:/c2960..../c2960...bin usbflash1:" (or usbflash0: depending on which port it was connected to).
I booted up the switch that wouldn't verify and tried to copy the image onto the switch from usbflash1: but it told me the copy command was unknown. Luckily, you can boot off the USB flashdrive image.
I typed "boot usbflash1:/c2960....bin" and it booted the switch where I was able to copy the working image to flash: "copy usbflash1:/c2960....bin flash:/c2960..../c2960....bin"
After overwriting the corrupt image, I rebooted the switch and it passed the verification on the image.