Replace cell PDH battery

[Rui_Yu]

        Action Plan
        ---------------------------
        1. Replace cell0 PDH battery.
        
               Example : Procedure to replace the PDHC on a RX7620.

               NOTE: This procedure assume a single partition system.
               
               1) Log into the MP, then select the console
               MP:co
               
               2) Gracefully shut down the host.
               # shutdown -r now
               
               3) Wait until the system restarts and  the EFI boot menu appears. Use the UP or DOWN arrow to stop autobooting.
                  Select the 'EFI Shell[Built-In]'.
               
               4) Save NVRAM variables
               Shell> fs0:
               Shell> variable -s
               --This creates a file named 'efi.save' in  this directory. This file contains the NVRAM variables.
               CTRL-B                                <<to return to the MP menu.
               
               5) Power off the cabinet.  Housekeeping power must remain.
               MP> cm
               MP:CM> pe , option 'T' to turn cabinet power off.
                  <<Housekeeping power remains on. DO NOT REMOVE external power to this machine.

               6) Replace the battery
               -- Remove the appropriate cell board. Remove the top cover. Replace the PDHC battery
               -- Insert the cell board.
               
               7) Apply power to the cabinet.
               MP: CM> pe, option 'T' to turn power ON.

               8) Move to the console
               MP:CM> ma
               MP: co
               
               9) Stop autoboot, then select   'EFI Shell[Built-In]' . Verify NVRAM variables.
               If the Debian boot options are not listed in the EFI boot menu,then do:
               Shell> fs0:  
               Shell> variable -r
               --- this will restore the NVRAM variables store in the 'efi.save' file.
               --- Set ACPIconfig:

               Shell> acpiconfig single-pci-domain      (*** same setting to rx7620/rx8620)
               Shell> reset
 
               10) Allow the system to autoboot.