Since you can't backup the original NANJG firmware (it's protected, you only get garbage if you try), you can't restore it's functionality if you flashed a new firmware to it (or messed up...). Here's a firmware that is somewhat similar (i.e. the mode group is selected by solder bridges between stars and the outer ring), but with more and different groups that seem to be needed more often (no blink modes).
2nd star chooses between 3-mode and 4-mode (i.e. if there's a moon mode or not),
3rd star chooses between low-to-high and high-to-low mode order,
4th star chooses between classic memory and no memory.
(and the 1st star of the NANJG is a dummy and not connected anyway.
Those options can be combined; that gives 8 mode groups (e.g. choose 2nd and 4th star for moon/low/med/high, no memory)
The levels are 5%-33%-100% and optionally a moon mode (a few milliamperes, depending on hardware variations like LED voltage).
It also has a PWM frequency of 18kHz, which is not visible and not audible (no whining noises), and it reduces brightness when the battery is low.
It is available for download as a hex file here (also there are more details).