Fortianalyzer FAZ-400E no boot partition

Hi All, 

I got a Fortianalyzer FAZ-400E from work decommission device, and the fortianalyzer does not comes with any hard drives. 

I read the manual and it says originally comes 4 x 3TB drives so I put my own 4 x 3TB WD NAS drives in the FAZ-400E. 

And turn on the FAZ-400E and it boot to fortinet logo and then nothing afterwards. I press "del" key into BIOS, and I go to check boot option and from the boot list, there is boot partition. 

How can I rebuild the FAZ-400E from scratch? Any help is much appreciated. Thank you.