If you have a user who is using EEMac and has applied the latest Thunderbolt update you may find that their machine goes into an endless reboot process after they authenticate at pre-boot. Some customers took the step of wiping the machine and starting again. While that will work, there is another way to get the machine to boot properly again without losing the encryption or any of the user's data.
Please find the below steps that need to followed in order to update the latest SMC firmware updates on thunderbolt machines.
Senior Product Manager
Endpoint Encryption for PC/Mac