I had the same problem with an ISR 4221. What i did and work is the following: Enter Rommon and Change the config-register vlaue to 0x0 to ignore the boot variable configured in startup config rommon 1 > confreg 0x0 After that i did a reset rommon 2 > reset This will bring router into ROMMON mode once again. Now change the config-register value to 0x2102 rommon 3 > confreg 0x2102 and next i had the actual IOS.bin on a usb and boot from usb rommon 4 > boot bootusbo:isr4400-universalk9_ias.16.09.02.SPA.bin Router booted with that image and then i was able to enter global configuration mode and change the boot. Copy the ios image on Flash from usb and then change the boot ROUTER(config)#boot system flash bootflash:isr4400-universalk9_ias.16.09.02.SPA.bin After that save by issuing ROUTER#wr Once the router restarts you will see that it loaded the new ios image and everything will work as should. Hope it helps
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