Press ON & F4 (push ON let it push and F4).
It will display the version on the top row of the HP 39gII Diagnostic Screen.
For example:
Version 30/Oct/2013 Rev 19148
Version 04/Sep/2012 Rev: 17818
Note: Firmware Update comes together with HP 39gII Connectivity Kit.
Soft Reset (does not clear memory, App parameters and program codes) Press ON & F3
Hard Reset (clear all memory and program instructions) Press ON & F1 & F6