2008 Volvo V50 Tailgate lock

Have you checked to make sure the solenoid is responding when you hit open? Is the noise from the solenoid? Is the solenoid loose or damaged?

I'm not that technical and not sure how I would check that. The noise sounds like an electrical motor spinning when I depress the tailgate button above the number plate. The noise is coming from the lock area. I cannot access or see anything and there is no way of opening the tailgate!!

Appreciate any advise you can give!!

It sounds like it is trying to work. Chances are something has come disconnected with the linkage. The only way to access the linkage and check things is through the inner door panel.

I managed to take the tailgate interior off last night. I then unbolted the lock mechanism and could, therefore, open the tailgate.
I took the lock mechanism out but it's a fairly sealed unit. The noise just sounds like a motor spinning and stripped gears/cogs!!
There doesn't seem to be easy access to the units internal workings.

They are sealed and not designed to be serviced. If all linkage is good and there are no visible problems, the unit itself must be bad as you described.

Not sure what linkages I'm looking at. There is only an electrical plug into the unit. It's getting power fine hence the noise but still not operating.
I decided to order a replacement from a beakers. Thankfully I've managed to secure one but I was advised by 2 volvo breakers that they get calls for these items all the time. It's obviously a common problem.
Thanks for tour advice.

Glad to help. Let me know how things work out for you.