Jag. X type estate boot lid window opens when ignition is switched on

Have you checked to see if the actual wiring to the motor has power? If you are getting nothing at the button it may not be the motor causing the issue. The emergency release is a mechanical pull so it is seperate to the motor.
Have you checked the fuses? There is a fuse for the tailgate in the dashboard fuse panel. With the drivers door wide open the fuse box is behind a pull off cover on the flat end panel of the dashboard. You need to check fuse 19 labelled 'T/LID'. It will be a 15A fuse, (usually blue).
Try this website for a Diagram of the fuse panel.

https://fuseandrelay.com/kia/ceed.html

Electric boot release, while the switch or the release solenoid might have failed, the most common cause of problems is one or more broken wires in the harness where it jumps from the body to the tailgate or boot lid.
The last time I tackled one of those I was fortunate enough for it to be on an estate model so it wasn't too difficult to get inside, remove the trim and using a slave battery and a couple of jumper leads to energise the lock.

Locking/Unlocking the doors from the outside
This is done using the RENAULT Card; see the "RENAULT Card" information in Section 1.
In certain cases, the RENAULT card may not work:
- if the RENAULT card battery is weak, flat, etc.
- if equipment operating on the same frequency as the card (mobile phones, etc.) is used;
- vehicle located in a high electromagnetic radiation zone.
It is then possible:
- to use the key integrated into the card to unlock the front left-hand door;
- to lock each of the doors manually;
- to use the interior door locking/unlocking control (refer to the following pages).
Using the key integrated in the RENAULT card
Insert key 1 into the lock in the driver's door and lock or unlock. Locking the doors manually
Turn screw 2 with the door open (using the end of the key) and close the door.
This means that the doors are then locked from the outside.
The doors may then only be opened from the inside or by using the key in the front left-hand door. Interior locking/unlocking door control
Switch 3 controls the doors, boot and, depending on the vehicle, the fuel filler flap simultaneously.
If a door or the tailgate is open or not closed properly, the doors and tailgate lock/unlock quickly.
If you need to transport objects with the boot open, the other opening elements can still be locked: with the engine stopped, press switch 3 for more than five seconds to lock the other opening elements.
Locking the doors without the RENAULT card
For example, in the event of a discharged battery or the RENAULT card temporarily not working, etc.
With the engine switched off and an opening element (door or boot) open, press and hold switch 3 for more than five seconds.
When the door is closed, all the doors and the tailgate will be locked.
Unlocking the vehicle from the outside is only possible with the RENAULT card in the vehicle's access zone or using the key integrated in the RENAULT card.
Door and tailgate status indicator
With the ignition on, the warning light integrated in switch 3 informs you of the locking status of the opening elements:
- indicator light on, the doors and tailgate are locked,
- indicator light off, the doors and tailgate are unlocked.
When you lock the doors, the indicator light remains lit and then goes out.

If there isn't an emergency "lock knackered" panel in the tailgate trim, you will probably have to force the trim panel off. These are usually only fastened by plastic pop studs, so you should be able to do it without damaging the panel, although you may need to get replacement studs.

When the tailgate is fully closed, is it actually properly latched down? Try pushing down firmly on the tailgate when it's closed just to be certain as it's possible that the latch is sitting half open at the moment.

Use your ignition key to unlock the boot (trunk) by inserting it into a small keyhole under the chrome lift on trunk lid. It took me a while to figure it out when I first purchased my jag.

Sounds like it too yours truely here my old jag makes a noise like that but its still working so who knows for how long and my ford escort tailgate BOOT in the queens english. stopped working years ago but their is nothing inside the car to steal ? thats if i bother to lock it in the first place anyway

hi if its the type that has the pop up rear window in the tailgate its most likely that there is water in the lift switch to the tailgate glass the one which sits in the rear wiper mounting sometimes when you pull away in the car rapidly the boot will click open is another symptom a replacement switch button is all you need

Emergency operation of rear lid
If the rear lid cannot be opened with the radio
remote control (e.g., if the battery of the remote
control is dead), the emergency operation must
be performed:
1. Unlock and open the driver's door with the
vehicle key.
2. Switch on the ignition so that the alarm system
will not be triggered.
3. Check if the TAILGATE function is activated in
the multi-purpose display of the instrument
panel.
Please observe the chapter “TAILGATE” on
Page 119.
4. Press the central locking button in the armrest.
The rear lid is now unlocked and can be opened
with the unlocking handle

change the rear glass open button  90% sure

I had the same problem with 2005 estate it used to open when starting the engine but does not unlock at all. The problem is the the sensor on the glass tailgate handle where the wiper arms is. It will cost around £70 from Jagaur themselves as I have just got one.