Hello,   Since it has been sitting unused, I would suspect it's no longer under contract?   The service contract is what maintains your license for the firmware and associated software Dell provides for the PS Series SAN.   So you won't be able to upgrade the firmware if that's the case.  If it somehow is, then you'd download the firmware from the eqlsupport.dell.com website, login required.  The upgrade would take quite a few steps.  4.2.x->5.0.10->5.2.x->6.0.x->7..1.x->8.1.x->9.0   Which is current.   There is a firmware u;grade guide with each firmware release that includes a chart with this into.   Note, firmware upgrades do not ever require removing data or resetting the array.   Once you do gain access to the switch you'll want to upgrade that as well.  Many fixes associated with iSCSI for that switch.   
recently took over administration of a PS6500E 42 1TB drives, M1000 , PC6224 these units have sat unused for several years. ~5-8  I dont think it was ever used !  Time has been limited to undertake this task, however, I have downloaded and read though lots of documentation as time permits. . Taking small steps to verify functionality of the hardware was my first priority.  SIMPLE hardware overview: > PE R710 > PS6500E > PC6224 > M1000 w/ 16 blades  < START TESTING> --> create an account on the Eql support site --> created an account here! --> Documented the original config wiring, network topology. --> All firmware documented on all units ( dont have on hand as I write this aaarg!) --> re-cabled , stripping everything out and restarting at a know topology. (KISS) --> Rebuilt head-node R710 with RHEL-6.8. --> Rebuilt all Blade Servers (16) with RHEL-6.8 --> created user accounts for testing on all systems --> installed use required SW for development --> Explained to the users this is the testing stage ONLY  --> Users started testing functionality, ( adding more requirements along the way ! ) --> Explained to the users this is the testing stage ONLY. LOL --> Users testing functionality, ( adding more requirements, You get the picture im sure) --> added 144G RAM to the head-node. ( 8G Originally ) --> Added 8TB USB drive for data storage ( user did this ..aarg! ) --> NFS share (8TB USB) from head-node to BS1-16 ( more requirements added ) --> Created test user account on the NFS share /users/home and accessible across all systems At this point I need to get the PS6500E online ant tested before this monster grow out of control. I was able to gain access to the unit via serial connection resetting the grpadmin password and running setup via command line.  I now have access to the GUI and performed some testing to the point of creating and connecting to a new volume via iSCSI to the head node.    --> Network config overview: --> MGMT == 192.168.1.0/24 ( IPMI / Dell mgmt?) CMC --> Compute == 192.168.2.0/24 network comm. head-node and the 16 blades --> PS6500 / R710 iSCSI = = 10.0.50.0/24 network comm. head-node and PS6500E --> PC6224 == Have not gained access to this unit, yet.  Seems like a flat configured swx --> M1000 2 x SWX modules and 2 x CMC modules connected together and 1 cable to the PC6224 --> KVM interconnection works to all nodes ( never use it though )  What is the best path to get the firmware on all this stuff updated and at the current version.  I'm not worried about data loss at this point.  Remember we are TESTING!!!  Thanks for taking the time and I appreciate any help, advise, comments.  
PS6500e Firmware 4.2 upgrade path and best practices