My car use to do that. If someone locked it with the key it wouldn't open with the central locking. Open it with the key....open the doors and then lock it again.
Many many years ago when my husband was rallying in the Borders, we were driving the Service Car and found that we couldn't get the boot open to get at the tools.
My husband's face was a picture when he drove passed us after the Start of the Rally to see us using a crow bar to get it open. It worked.