Hi Samuel,
If the IOS of the 2503 is damaged, usually the router will boot up in boot mode, if this is the case then you have to download a fresh copy of the IOS from CCO and upload it using TFTP, if the router is stuck in rommon then the procedure is the following:
There is only one way to install an image on the 2500 Series Routers if the main Cisco IOS software has been deleted or corrupted. You must use its boot image.
Since you have already determined that the cause of the router booting up in ROMmon is not due to the configuration register value, the only option available for recovery is to re-install or upgrade the Cisco IOS software from a TFTP server using the built-in boot image (Rx-boot) in ROM.
To get into the Rx-boot mode or boot image, do the following:
If the rommon prompt is "rommon # >", type:
rommon 1 > confreg 0x2101
You must reset or power cycle the router for the new configuration to take effect:
rommon 2>reset
System Bootstrap, Version 12.0(6r)T3, RELEASE SOFTWARE (fc1) Copyright (c) 1999 by cisco Systems, Inc.
UBR924 platform with 16384 Kbytes of main memory....................... If the rommon prompt is ">", type:
>o/r 0x2101
>i
System Bootstrap, Version 11.0(10c)XB2, RELEASE SOFTWARE
Copyright (c) 1986-1994 by cisco Systems
2500 processor with 16384 Kbytes of main memory
Restricted Rights Legend
Use, duplication, or ................
Once the router is up in boot mode you have to perform the copy tftp flash procedure.
Hope this helps
