With the first method, you will need to be sure the switch has a connection to the server hosting the file. With the second method, you will need to send the file to the switch via the terminal software.  Here is an example of how to send the file: [URL] Let me know if this is what you are doing and it still is not working.
Hi,  I have tried to upgrade the switch IOS however both images have been corruped. I am unable to get to the boot menu. Once the switch has been restarted it goes directly on u-boot > please see the following script Writing to Nand... done /image1 not found ! ubifsload - load file from anUBIFS filesystem.   Can someone please advise.
Switch N2048 Uboot