Denso BHT-8000 User Manual page 158

System down error
! Problem
An error has occurred during execution of System Program.
If this error occurs, the BHT beeps five times (for 0.1 second per
beep).
! Solution
Unload and reload dry cells or battery cartridge, then turn the BHT on.
If this error occurs frequently, make a note of the message and codes
on the LCD and contact your nearest dealer.
145
Chapter 4 Error Messages