So, couldn't get it to power on at all... opened up the case. Never soldering anything before. Anyone soldered this? I took off the spring, and that didn't help (still does not turn on).
Here is a pic:
https://www.dropbox.com/s/o96dwauos4m0fkb/20150806_161207.jpg?dl=0
I just fixed my RT-N66U today. It's a bit more involved than I thought but I'll try to explain in words since I don't know how to attach a pic:
1. Remove 4 screws under rubber feet
2. Use credit card to unclip case on all 4 sides
3. Remove the spring and the clip holding the spring on the button
4. Super glue the button down in the "on position" (Just like you, I thought I was done but when I plugged the power back in, I noticed that the router is still not powered on)
5. Flip the circuit board over and remove 6 tiny screws to detach the back shield/ground plane/big shiny metal plate!
6. With the power button pointing down and looking at the back of the circuit board where the power button connector pins are sticking out , you will see that the connector has 5 pins.
7. The top right and bottom left pins aren't connected to anything and is just there to hold the connector onto the board. The remaining 3 pins in the middle, you will want to solder a short wire between pin 1 and 2 (You can blob it if you have mad soldering skills!). Pin 1 and 2 are farthest away from the actual power button and if you look at the pad on the board carefully, you will see that they are both round with pin 3 having a square pad.
FYI, Step #4 is necessary even if you're soldering the pins together because with the spring in and the power button stuck in the off position, it is actually connecting pins 2 and 3 together. It's probably not a good idea to connect pins 1, 2, and 3 together on that connector.
Hope that helps someone who wants a clean (aesthetically) solution but I would not recommend it for people who don't know how to solder or not a bit adventurous.