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 start

Caution:
The following process will clear all data in PT630 RAM disk memory) Reset (cold start) the PT630, press [CMD], [BackUnitech PT630 back key] and [Unitech PT630 key reset]  
simultaneously, press [3] 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.
Unitech PT630 hard reset

General advice: Before you buy a new cell phone or new tablet, please try the following procedure to repair your device in a software way. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before doing factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.! Please also note, that a hard reset operation will not unlock your mobile phone's SIM lock or network lock, but it will remove the unlock pattern, remove the user password or PIN password (NOT the SIM card's 4 digit PIN code). Also note that the firmware version will not be affected in any way, it will not be downgraded, it will remain the same you are using and if you have rooted your device, root privileges remain also unaffected.