To reset a profile hold down the number of the profile you want to reset (1-4) then hold down the select button at the same time. The scale will ask you if you want to erase. Then you can recreate your profile.
The Model 613 DC4300 (from year 2000) does not have a battery cover door. It is possible to disassemble it and replace the CR2032 battery. Peel off the label on the bottom. Under it is an oval cover held on by adhesive. Peel that up and remove two Phillips screws. The whole black plastic back plate is one piece, and I had to break little tabs on all four corners to get the back off. Under the back plate, the battery cover is held on by three more screws.
The battery is located behind the LCD screen, slightly on the right hand side side if you are facing the LCD screen. You can drill a hole on the platic case from the back of the scale, and you will see the battery house and 3 screws on the battery house lid, unscrew the 3 screws, you can take out and replace the 3V Eveready button type battery easily.
I have tried to open the case by taking out the spring latches located behind the 4 legs of the scale, it was much harder to put every thing back afterward.