My power button would not press down, or was stuck down...just didn't work right.
Repair went amazing. Apparently someone had taken my phone apart before because there were 2 screws missing from inside and all of the sealant that was supposed to make it so difficult to get the screws out, was already broken free. I took it apart and put all the screws and parts in an egg crate with the numbers for the steps. Reversed the steps and put it all back together and I was amazed it booted, even more amazed that everything else worked.
Read all the comments on the repair guide you are using. Some of the steps are copy and pasted from other repair guides and are related to other repairs and can be skipped for what you are doing. You really won't know this unless you already know what you are doing, or you read the comments.