Like JamesS, I seriously considered paying for professional installation. Although some projects appear to be simply that of unplug-and-replace, my first and only installation of any kind was in a (narrow-hood) DCC-ready Proto SD9. Without a mentor, I have relied on reading and viewing similar installations, only a very few of which are available for Railpro, and none for my loco.
It was interesting, but time-consuming to disassemble the loco, then remove the PC board, remove and cut down the weight so as to fit the LM-2S, replace the lights and then splice in the output leads. Almost perfect, except my soldering skills are clearly sub-standard, as a loose splice causes stalls.
My point is that for first-timers, most projects can seem intimidating. When I hear 'how simple xyz is', I feel even more ignorant when it isn't simple for me. I still am intimidated, as I expect to completely replace the faulty work. On the other hand, it is enjoyable to learn new skills, and I am most thankful for the advice of others in such forums. Hopefully I won't fry anything more expensive than a LED!
I truly appreciate the generosity of time and talent shown by those who have these skills to those of us who are learning.
JimW (definitely NOT an expert here!)