It's a complicated job. The power supply sits in the bottom of the housing and all components, save for the optical drive, hard drives, and the fan(s) in between the two, come out. That means the processor, all fans, and all parts in between must come out, logic board included. The liquid-cooled processor is one unit, and it does not come apart further. Once it's loosened from the logic board, it gets pulled straight up and out. (Never place the processor pin-down on any surface for any reason.)
I've performed this job countless times and still despise it to this very day.
__________________ ACMT MacBook Pro (15-inch, Mid 2012) 2.3 GHz Core i7, 16GB, 256GB M4 SSD iPhone 8 - 64GB S/G • Sound System Audio Engine A2 • Display UltraSharp U2412M 24" Custom Built Gaming PC Kaby Lake Edition | 16GB DDR4 | GTX 1070 8G
I have not had to do the job Lars describes, but I've assisted other techs doing it, and he's absolutely right: even by Mac Tech Guy standards, it's a BEE-OTCH and not something any sane person wants to get involved in, unless you like scraped knuckles and loads of frustration. That price would have be pretty ridiculously low to tempt me into doing it.
Do I need special tools to do this job? I have regular and small slot, philips, hex and torx screwdrivers. Also have a jigsaw, circular saw, spiral saw and chain saw. And can curse in several languages. :-)