If the O/S flash becomes corrupt, the symptom is usually a “grid” of lines on the LCD when it is switched on. The recovery from this situation is simple, as the onboard EPROM bootloader can re-program the flash from USB or a SmartMedia card.
The following instructions are taken from the REB1100 Files Yahoo group, re-written for my idea of clarity. This, of course, may bear little or no relation to your idea of clarity.
Note that I have not had need to try this myself, so don't blame me if this scews up your device more than it already is.
Now we're ready to upload the new firmware image and support files to the device and run it. When you run the first command below, the backlight should switch on.
rebtalk put code ram.rff rebtalk put code sysicons.rb rebtalk put code rocketbook.ini
The device should now be working again. However, it's running the new firmware image out of RAM, and will revert to the corrupt flash when switched off. These commands write the files into flash.
rebtalk put ram.rff ram.rff rebtalk put sysicons.rb sysicons.rb rebtalk put rocketbook.ini rocketbook.ini
The firmware is now saved into the onboard flash. You can turn the device off and back on to test whether the update worked.
If the update did not work, there are two possibilities. One, the ram.rff file you used is a newer version. This technique has only been tested with 2.0.240, so try again with that one. Second, Gemstar added some tricks in the later unit's booteprom to stop us recovering from corrupt flash ourselves. If that is the case with your unit, go back into the Command Prompt and try these steps first.
rebtalk command 1 rebtalk command 3
Now, continue with all the other rebtalk commands and you should be good to go.