Hello, I'm sorry to resurrect such an old thread, but I have the exact same problem with my DSP4000. I've ordered the replacement powered RAM chip (texas instruments BQ4013YMA–120) and replaced it, but the error persists. Are there any other possible reasons? Any insights will be much appreciated!
Did you do the reset to factory defaults ? If not, do so.
If you did, look at "Fixing internal memory problems" in the UM. If you follow this, and still get the message, it is possible that your new ram is no good.