I did manage to successfully remove & replace my iPhone 5 battery. But since then, my screen flickers a little at the bottom & it also just randomly turns off now & then (obviously this could be an issue caused by the actual battery that I replaced the original one with) - and it is obviously in no way, ifixit's fault.

But I just thought I should comment & let people know that this is NOT an easy task, and it is VERY EASY to accidentally damage other internal parts of the iPhone whilst completing this task, so if you're going to do it, then follow the instructions VERY carefully - or have someone a bit more 'tech savy' do it for you :)