Identify the fob before opening it
Use the owner's manual for your vehicle year, model and key arrangement. Do not choose a battery solely from the brand name or a picture of a similar remote. Different items can use different cells, access methods or servicing arrangements.
Follow the documented opening method
Check whether owner battery replacement is supported and use the tools and opening point specified in the guide. Do not assume every fob contains a removable emergency blade or a case that should be pried apart. Stop if the housing resists or the instructions do not match the item in your hand.
Replace only what the instructions specify
Use the documented battery type and orientation. Avoid bending contacts or manipulating a circuit board in an attempt to diagnose an unrelated fault. Keep removed parts together and follow the manufacturer's instructions for closing the case and normal operation afterwards.
Keep small batteries secure
Keep new and used button batteries away from children and pets, and follow the battery manufacturer's handling and disposal instructions. Make sure the battery compartment closes as intended before returning the key to everyday use. Do not leave loose batteries where they could be mistaken for another object.
If the remote still does not respond
A battery replacement does not diagnose every key problem. Report which functions fail, whether the vehicle starts and whether another key works. Ask for model-specific advice rather than repeatedly changing cells, bending contacts or following an unrelated programming sequence.
Related services and enquiries
Compare lost-key replacement with spare-key duplication, or read about key fob programming. Check published price guidance and send your vehicle details.
Source and further reading
Ford owner manuals: choose the correct vehicle. Check the guidance relevant to your own vehicle.