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54501A error: Cal ram write protected

Question asked by asauter on Oct 12, 2008
Latest reply on Oct 7, 2011 by ateneycke

On power up the instrument says "Cal ram checksum error re cal instrument."  then when i try to calibrate, util->selfcal gives error "cal ram write protected."  receive same error in util-> service.   Running selftest I have 

failed protected nonvolitile ram
failed D/A converter
failed A/D converter

i searched this forum and post topic: "cal ram checksum error (HP 54501A) ".   except for the "cal ram write protected" error, the poster had the same experience (checksum error, and selftest fails).   They recal'd and got scope to work.  A dead battery was likely cause of checksum error. 

Hoping i have a dead battery and that my selftest results are incorrect.  Is that reasonable hope?  what might cause the 'write protected' error???