Laptop froze, and when I hard-shutdown and restarted, it hung on the flashing question mark in a folder screen. It's too old for the Apple Store to work on, and the interwebs told me to replace the cable.
I was super-freaked out to have to touch the battery connector and the logic board, but the guide was very easy to follow. The only problem I had was trying to place the sticky part of the new cable on the case; it took a while to figure out the best positioning... but, I mean, that was all of 30 seconds and not actually relevant to whether the repair was done correctly.
Followed the instructions in reverse order, sent a little prayer up, hit the power button, and cheered when the little apple came up on my screen! I felt like an amazing engineer.
Read the instructions first. Don't rush. Go step-by-step. Have a place to put all the tiny tiny screws picked out beforehand.