The file system is broken on the PBX or the PBX doesn't switch on.
Perform a reflashing procedure as described below.
Important: this procedure can be applied only to PBXs with Atom and Celeron Processors (in production since 2015) having a MSATA SSD, see the picture below to know whether this procedure can be performed on your PBX
Eject a hard disk drive (HDD) from your PBX system
Note: See the picture below to understand what the HDD looks like.
Important: perform this procedure only if HDD looks like on the picture below!