Ok, can't see anything in the manual so not sure what else to suggest?
Just found the text below, wondering if the new cover has held the lock button in and it's deactivated the keyless entry? It's on page 98 in case it helps.
Keyless Access temporary disconnection
function*
You can deactivate the vehicle's Keyless
Access unlocking for one locking and unlocking
cycle.
● Move the gear lever to position P since
otherwise the vehicle cannot be locked.
● Close the door.
● Push the central locking button on the
remote control and touch the locking sensor
surface of the driver door handle
››› Fig. 73 B within the following 5 seconds.
Do not grasp the door handle; otherwise the
vehicle will not unlock. Deactivation is also
possible if the vehicle is locked through the
driver’s door lock.
● To check that the function has been deactivated,
wait at least 10 seconds, grip and pull
on the door handle. The door should not
open.
The next time the door can only be unlocked
via the remote control or the lock cylinder.
The next time the door is locked/unlocked,
Keyless Access will be active again.
Keyless Access permanent disconnection
function*
You can deactivate the vehicle unlock with
Keyless Access permanently in the infotainment
system so that others cannot unlock or
start the vehicle.