I'd 1st try resetting the ECU by disconnecting the battery cables and clamping them together for 10 mins. Remove both battery leads from the battery then use a nut and bolt or G-clamp to hold both battery lead terminals together.
This discharges any capacitors / memory within the ECU and around the car so ensures all memory settings are wiped clear - back to the factory default.
This will reset all the systems on the car and you'll need the radio security code to get it going again, and ensure that the keys are in your hand when you re-connect the battery as the car may lock and turn on the alarm
then re-synchronise the key as follows:
The Central Door locking is controlled by the Multi-Remote Control system which controls the door locking, door super locking and hazard reminder. When the doors are locked and unlocked the unit flashes the hazard lights once for lock and twice for unlock.
A maximum of four remote controls are allowed to be programmed.
Ensure all the doors have been unlocked, either by using a good transponder key or remote control plip key.
1. Turn the ignition switch from Position 0 to ON 6 times within 10 seconds.
2. Then turn ignition switch to OFF position. Leave key in ignition switch.
3. After 2 seconds, the system will enter programming mode and will flash the warning lights twice.
4. Press and HOLD the unlock button on the Plip.
5. While pressing the unlock button, press the lock button 3 times.
6. Release the unlock button.
7. The warning lights will flash once to indicate successful programming.
8. Repeat procedure 4 to 7 for up to 4 plip key’s.
9. When completed turn ignition ON, and the warning lights will flash 2 times.
10. Remove key, and check all plip key’s for operation.
NOTE : The programming mode will stop when either the ignition is switch ON, 4 plip keys have been programmed or no input signal either from the switch or plip keys has been received for 120 seconds.