We bought new AIR-CT2504 controller. It came with default software 7.3.102. We thought of upgrading it to the latest 7.6.100 before implementing the devices in production. As per the release notes of the 7.6.100, a direct upgrade from 7.3.x to 7.6 is well supported. Following is the sequence of events as it happened:
1. Dowloaded and upgrade the controller image 7.6.100 using GUI. No error, upgrade completed successfully.
2. After the reboot, the version was still 7.3.102. This version was on backup partition. The primary image was 7.6.100, but it did not boot from it. Dont know why???
3. I read about the FUS upgrade required for some scenarios. I thought this could be the issue and so upgraded the 1.9 FUS through GUI.
4. After reboot, device never booted. System and other LED is amber.
5. During the boot I pressed ESC to go through boot options. It says that primary image is 7.6.100 and secondary image is "Bad Image File". Its bricked device and does not boot.
Now, I believe that RTOS is the only option to recover the device. But how do we get this RTOS file and instructions? Is it available somewhere other then Cisco TAC?