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Your fuel door lock is actuated by vacuum and if the vacuum system isnt working due to low voltage due to the main battery at fault or just weak needing recharged this may cause the locks to be inoperable.If you peel back the passenger side trunk lining you should see the vacuum line that attaches to the fuel door lock.In some cases you can tap into this line and apply vacuum to it to release the fuel door lock so you can open it or you might be able to see the lock actuator at the fuel door with the lining pulled back in the trunk to then actuate it or remove it by hand to get the fuel door opened.https://www.dropbox.com/s/kzjcz1mmkni3hv2/fue-12-20.JPG?dl=0
I have also tried the credit card method with sliding a card in between the fuel door and lock actuator to try and push the actuator lock out of the way or bending the fuel door striker to open the fuel door then re shaping the striker.
I suspect you may have a low battery issue with the trunk battery as this is the main battery for your model here.I would have it charged and see if it operates properly from there and the battery tested to be sure it is o.k.
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If your remote key has failed then it will need replaced as well here.
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