The most recent 701N firmware is 3.4.790 (freely available from Dell at
http://ftp.us.dell.com/utility/sup34790.exe ).
You also need the v3.4.790 version of
assist http://ftp.us.dell.com/utility/ast34790.exe.
To upgrade any further you need to:
1) convert your unit from a Dell OEM model to a standard Snap model (instructions have been posted on this forum in the past) - easy.
2) legally obtain a copy of SnapOS 3.4.805 - hard (no longer freely available from Adaptec/Quantum/Snap).
Good luck in your efforts.