A warm boot resets the system without clearing any RAM program or data files. Device configurations preserve the same values as they had before the warm boot. On the other hand, a cold boot will clear the RAM and initialize the PT630 to default values.
PT630D cold startCaution:
The following process will clear all data in PT630 RAM disk memory) Reset (cold start) the PT630, press [CMD], [Back] and 
simultaneously, press  in “Start Menu” press ENTER.
Make sure to back up your data in PDT before making the replacement the 3V 190mAH Lithium Data Backup battery.