It a pretty simple circuit in terms of modern auto electrics,, you either got electrical pulse at the lock when activated or you haven't . If you have then it tailgate latch side issue, if you haven't it fuse/wiring/relay/module/button related . 5 minutes with a multimeter and a basic scan tool should give enough data narrow down area to investigate further ... Latch actuator and button are quite common failures on these . This the problem with all this electrical crap on modern vehicles, mechanical principles of boot release/opening far better, lasts pretty much forever, less parts thus less environmental impact & if did get an issue it generally easier/cheaper visual inspection and adjustment/repair . Move onto something like a Tesla which rammed full of pointless low quality electronics and software and purposefully engineered barriers for diag/repair options and the drama and cost is literally insane ... Point here is buy vehicles with a lot of thought and take a lot more thought on how you spend money trying get repairs ... Don't assume newer is less maintenance and hassle as in my workshop reality is newer it is the more goes wrong and the more ballache and more cost to resolve it ...

My first thought would be wiring from the car coming through to the tailgate which is encased in a rubber gaitor. What tends to happen is when the tailgate is opened and closed it bends the wires to the point that they break. If this has occurred it is difficult sometimes to see it where it is located but you can also test for continuity with a multimeter. Also, if some wiring shorted out then possibly check all the fuses to see if any have popped. Also, check for all earth points leading to and from the tailgate for corrosion.

I would start with removing the bonnet switch, cleaning and examining it - test with a multimeter that there is continuity when opened/closed and also the connections for dirt, corrosion, etc. If all else fails then bypassing will work, but not sure how many thieves would pop the bonnet which they still have to enter the car to release so its not a major thing in reality.

I have a 2012 XV SE diesel and the tailgate has stopped opening. Thus far I have replaced the latch, replaced the switch in the tailgate, had the wiring checked (£85) only to be told it's not working! Central locking on all doors works fine from key and door lock on drivers door but the tailgate is dead. Apparently all the wiring form car through to tailgate is fine . Any ideas where to look next please?

South lanarkshire