Can you replace the battery in an RX8 keyfob? If so how do you open the FOB. I've managed to seperate the key from the alarm but I can see no obvious place to get to the battery.

anon,
not told what car maker , model or year it is. (fail)
nor if you have only 1 fob, not 2 fobs that is super wise to do.
as in KEY FOB
now a pure generic answer,
All doors locked, not and will not open, guess yes locked
so the KEYFOB battery coin cell is now dead, as all do at 5 to 7 year.
the glove box users guide tells you how to replace the keyfob battery.
https://fobbattery.com/

each maker of FOB has there own way to open the FOB
so do no wreck the FOB guessing, why not tell what car this is first. and above damage in a panic.

once the doors open , we then run into the cluster security lamp
if key on fails now say so and what the lamp does. security.
never have 1 key for 1 car, that invites, costly tow service and costly reset of security systems onboard

never have just 1. fob. or it can be painful.
lost key , bad keyfob. drowned. or crushed, or flushed.

Pull the fob apart. It will open up and you can push the button back in place. No other options unless you have a second fob. If you do, remove the battery from the bad fob and only use the second fob.

If you lock the car with the key, you must open it with the key, or alarm will sound. If you lock on fob you must open on fob. If you use ke y, place in ignition quickly to silent alarm. Good luck

The alarm is armed if keyfob is used. So you must use the fob to disarm alarm first. So someone can not unlock and open door without keyfob or alarm will be set off.

Try with brand new key fob battery and see.If that helps.
Otherwise May be keyfob needs to be reprogrammed.

KEYFOB PROGRAMMING

Keyfob remote reprogramming is not very difficult but on some cases it can be done by dealer service tools.

If the remote s faulty then key fob will not get programmed.

Insert the key in ignition. Turn the key to on position, and cycle the key three times off-on-off-on-off-on. Then with the key fob remote select your remote and then try to operate the vehicle with remote.

These are just the basic procedure, but sometimes it will not help.

On that case dealer is the only option.

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There are few much related troubleshooting links mentioned below for remote key fob reprogramming. I suggest you to go through the list and click the link below to go through its details and procedure: -------

2009 Toyota Highlander: Smart Key Not getting Detected?

http://whatisbyme.blogspot.in/2012/05/2009-toyota-highlander-smart-key-not.html

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2007 Toyota Prius: Reprogram Remote Keyfob?

http://whatisbyme.blogspot.in/2012/05/2007-toyota-prius-reprogram-remote.html

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Pin that holds the flick key part to the key fob?

http://whoisbyme.blogspot.in/2012/07/pin-that-holds-flick-key-part-to-key-fob.html

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2006 Toyota Hilux: Programming New Key?

http://technoanswers.blogspot.in/2012/04/2006-toyota-hilux-programming-new-key.html

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Where is Key chip memory located on 2004 ford Freestar?

http://technoanswers.blogspot.com/2012/01/where-is-key-chip-memory-located-on.html

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Ford Keyless Remote Fob Reprogramming?

http://schematicsdiagram.blogspot.com/2011/12/ford-keyless-remote-fob-reprogramming.html

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After getting car washed, check engine light is ON and key less entry not working, tried reprogramming. Also car shows fuel pressure?

http://schematicsdiagram.blogspot.com/2011/12/after-getting-car-washedcheck-engine.html

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Audi A8 Key Fob Programming?

http://technoanswers.blogspot.com/2011/12/audi-a8-key-fob-programming.html

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Oldsmobile Aurora Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/olds-aurora-key-fob-reprogramming.html

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Buick Lesabre Key Fob Reprogramming?

http://technoanswers.blogspot.com/2011/12/buick-lesabre-key-fob-reprogramming.html

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Keyfob remote not working on 2003 Ford E350 Econoline?

http://technoanswers.blogspot.in/2012/01/keyfob-remote-not-working-on-2003-ford.html

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KeyFob will open the doors but not start on BMW?

http://technoanswers.blogspot.in/2012/02/key-will-open-doors-but-not-start-on.html

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Mitsubishi Car Key Not getting detected after replacing ECM

http://repairhelpcenter.blogspot.com/2012/11/mitsubishi-car-key-not-getting-detected.html

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Key Fob will not lock and unlock doors?

http://technoanswers.blogspot.in/2012/02/key-fob-will-not-lock-and-unlock-doors.html

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2000 Jeep Cherokee Limited: KeyFob Remote Not Working?

http://schematicsdiagram.blogspot.in/2012/06/2000-jeep-cherokee-limited-keyfob.html

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Chevrolet Malibu: Key Stuck in ON position?

http://technoanswers.blogspot.in/2012/04/chevrolet-malibukey-stuck-in-on.html

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Theft indicator not letting car to start?

http://technoanswers.blogspot.in/2012/02/theft-indicator-not-letting-car-to.html

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2012 Dodge Ram: Ignition Key will not release?

http://whoisbyme.blogspot.in/2012/07/2012-dodge-ram-ignition-key-will-not.html

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These details will help.

Thanks.

1.)I would recommended that you ensure all key fobs are fitted with new batteries. ( Click here to see battery replacement guide).
2.)Get in the car and close the drivers side door.
3.)Put the key into the ignition and turn to position I.
4.)Wait 5 seconds
5.)Turn the key quickly to position II then back to I four times.
6.)You should hear a single chime.
7.)Remove the Key
8.)For each Keyfob in rapid succesion. Press any single button on the keyfob you wish to pair, you should hear a chime as each Keyfob is paired with the security system. After the chime do the next Keyfob.
9.)Check operation of each Keyfob.

See http://www.bluejag.co.uk/X-Type-keyfob-reprogramming.php

Open the door and immediately place the key in the ignition, that will shut off the alarm. The batteries in the Keyfob are probably dead and need to be replaced. You will see that the keyfob can be opened, though do it carefully, and you can replace the batteries. This will fix the remote. You may also have a valet button in the car which temporarily disables the alarm and will keep the alarm from sounding if the door is opened.

In case of a problem or clarification or my solution was insufficient, don't hesitate to post me a reply.

If you are satisfied, rate my solution with the "thumbs" or (even better) add a testimonial.

The alarm should turn off when you put the key into the ignition.

Also, check to make sure that the metal circle that you put the battery in is not loose. It should not wiggle much at all. If it does wiggle, it will need to be re-soldered onto the fob's electrical board.

Hope this helps!

try changing the fob battery .the freelander has a fob low battery warning tone that will start after the alarm has been deactivated by the fob with a low battery and will stop after the key is switched to acc. for any one wanting info on problems with freelander , goto this web site . http://www.myfreelander.co.uk/

Your key fob needs reprogramming, and yes the alarm will go off when you open the door, but you have enough time to put the key in the ignition which will prevent the alarm sounding. Car is usable until you get the fob sorted by locking and unlocking using the key.