In order to begin taking the old battery out of the unit, you must first take the BP1000 unit off of your grid. You should turn the unit off, unplug it from the wall outlet, and unplug any appliances that are hooked up to the outlets on the unit. Once your unit is off-line, following these steps will ensure that you have a successful (and smooth) install of your RBC6 battery. 

1. Remove the front plastic face plate from the unit (where the indicator lights are)
2. Once the face plate is off, there will be a metal latch which is secured to the units frame by two small screws at the very top, remove them.
3. Pull the latch down to reveal the spent RBC6 battery pack and slowly slide the pack out of the unit
4. Disconnect the closest spade connector first, then maneuver the pack till you can disconnect the second.
5. Remove the battery from the unit entirely
6. Assuming you have already purchased your RBC6 replacement battery, slide the new apc replacement battery into the battery compartment
7. Connect the first spade connector, which would be the one you took of last in step #4. Once the first spade connector is secured on your APC replacement battery, continue to slide it into the unit till you can easily connect the last.
8. Once the spade connectors are on the RBC6 battery and its been pushed as far into the unit as possible, its time to seal the metal latch back to the unit via the two small screws.
9. Once the metal latch is secured, simply connect the plastic face plate

Now your all done! You have successfully installed your own APC replacement battery without burning down your home office or IT room.