Modifying this post to say that the following steps worked well (as of today May 17, 2-14) to do the Firmware Upgrade (on a DS2072, ie, the non-A version) for FW v.3.
Rigol DS2000, DS4000, DS6000 Firmware Upgrade Procedure
Instructions originally Dated: 11.21.2012
Solution:
0. Check to see that the USB stick is recognized by inserting into the USB
input on the front panel. The instrument should indicate USB Device
Detected.
NOTE: If the device is not recognized, try another USB memory stick. We
also recommend minimizing the number of folders, files, and programs on
the stick. Drives less than 4GB in total volume are also recommended.
1. Download the proper firmware file and transfer to the root directory of a
USB memory stick. If you have downloaded the packed .rar/.zip file. Do not
forget to unpack and only copy the .GEL file to your USB stick.
2. Plug the instrument in to an uninterruptible power supply.
WARNING! Don't power cycle or disturb the instrument until the upgrade is
complete.. as the instrument can be damaged.
NOTE: USB Stick is not plugged in DS2000/DS4000/DS6000 at this time!!!
3. Press the power on button on the front panel of the instrument. All of the
buttons will light. At the same time press two or three times the Help key on
the front panel. All buttons will unlight
4. If you now can see the Rigol Logo on the screen you failed to go into update
mode. Please go back to step 3.
If the screen stays black and the Single light will illuminate (as below in the
picture) you can go ahead.
5. Now it is time to insert the USB stick into the front panel.
6. The CH1 button will flash and then go solid.
7. After 5-10 minutes, all of the buttons on the front panel will be lit. The
upgrade is complete.
8. Remove the USB drive and power cycle the instrument.
9. You can check the firmware revision by pressing
Utility > System > System info
--
A few observations:
In Step 3, as soon as the power button was pushed in I just kept quickly pressing and repressing the Help button (maybe 2-3 times very quickly), this seemed to be the best way to put the oscilloscope into the Firmware upgrade mode.
In Step 6, the CH1 button seemed to flashed for about 30 seconds or possibly somewhat longer.
Step 7 didn't seem to take nearly 5-10 minutes; maybe 4 minutes or so? When the CH1 button quits flashing and the front panel button lights come on nothing shows on the display. At this point Step 7 is complete and you can proceed to Step 8.