Having this same issue, Only way Ive found to resolve is reimage using the Dell Recovery Tool. 
Hello all, I faced some strange error saying the "Fatal Error: No zpool found in boot disk" on OptiPlex 3000 Thin Client(bios: 1.0.2, firmware 9.3.2102). You can simply reboot the thin client and the error will go away at next boot cycle. As I have several clients occured this error for same day, I suspected this related to number of improper shutdown(my environment use electrical time switch to power on / off the thin client at specified time period but not yet find information to prove this. [IMAGE] Do anyone face this error ? and how you solve this? Thank you in advance.    
"Fatal Error: No zpool found in book disk" on boot error for OptiPlex 3000 Thin 
Client