How to rollback update 1 package from ESXi5

 Access over remote console cards such as IMM, iLO, DRAC or direct attached screen:

1.    Reboot server
2.    Press Shift+r when the screen displays Loading VMware Hypervisor

ESXi5 recovery mode screen

•  Confirm selection – Y
•  Server restarts with an old build

ESXi5 build number before upgrade

Access to server via SSH

1.    Edit the files /bootbank/boot.cfg and /altbootbank/boot.cfg.
2.    In the bootbank copy of the file you should find updated=2.   It will be updated=1 in the altbootbank copy.
3.    Swap the values for updated, save the files and reboot.
Note:  the first way I mentioned using Shift+r is supported, the second method is not.