17 R1, GPU GTX 970m replacement help required

hello everyone!
So i need some help regarding GPU replacement. So my brother bought an Alienware 17 R1 back in 2014 (i will attach an image of the specs to this post) and now i currently own it. What happened was his GPU GTX880m went bust and he couldn't use the laptop because you can only see the black screen when you turn it on; according to the dell service center they said the issue was with GPU and it had to be replaced.
I've taken the laptop and i want to use replace the GPU. i bought a GTX 970m 6gb card from AliExpress recently (i will attach an image of new GPU to this post). There is no clear guide out there on what i should do once i replace the GPU.

Ok so this is the video ill be using to replace the GPU. Is this good enough? https://youtu.be/fh8ockwbDiE

After installing the graphics card, what should i do next so i can make the graphics card work properly on my laptop? Ive read in several places that i need use the UEFI mode and do something there but i feel slightly clueless. I've never done anything like this before so i am not sure what to do. Sorry for ignorance.

Anyways let me know how i should proceed. Help is much appreciated :).