Cisco 5548 rebooting because of fan removal

[lanman1960]

Hello I have a Cisco Nexus 5548UP 7.0.5.N1.1.bin that is currently hung.      In my initial troubleshooting the log shows that the system is shutting down because of detected fan removal.   

As show below:

2019 Feb 11 14:54:16 WTC1-SW-301 %PFMA-0-SYS_SHUTDOWN_FAN_REMOVAL: System shutdown in 45 seconds due to fan removal
2019 Feb 11 14:54:21 WTC1-SW-301 %PFMA-0-SYS_SHUTDOWN_FAN_REMOVAL: System shutdown in 40 seconds due to fan removal

After it counts down to zero the switch becomes hung and I cannot manage via console cable.     The only way to get back into the switch is to do a power reset which starts the process back off and within 50 seconds the system is back hung.    I know there is a bug in the earlier version of code 5.2.1.x that is very similar to this behavior and Cisco recommends to upgrade the OS to 7.3.3.N1.1 which I have downloaded.    The problem is the switch wont stay up long enough to download the new version.     Has anyone else seen this behavior and if so how did you upgrade the unit?

[lanman1960]

The bug I referenced is CSCuw48559

[Jason Leschnik]

Hi lanman1960, do you still see the fan countdown timer in the bootloader, it might be possible to break into the bootloader and TFTP a new fixed image to the switch.

The reset procedure [1] will require you to mash Ctrl-R while the switch is booting. Once you're in you can then setup the mgmt0 interface and TFTP a new image to the switch. Then you load/boot the switch from that new image. Give me a yell if you run into any issues. 

[1] https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/password_recovery/b_nx_os_pwr/nx_os_pw.html