I may have to replace my early 2013 15" Retina MBP. The keyboard membrane is finally going. This started about 6 months ago where the power button was sketchy trying to turn it on. Now it doesn't work at all and I never shut it off until I go to bed. I have it automatically wake at 3am in case I get up early. If I bring it anywhere I just close the lid.
If I accidentally turn it off I have to physically open the bottom (9 tiny screws), disconnect the battery with a spudger, then reconnect it after a minute, replace the cover and plug the magsafe power cable back on. That's the procedure to boot a MacBook without a power button.
That was somewhat livable, but now the E, C, I and down-arrow buttons have started missing connections too. So, it's time.
The battery I replaced in it a while ago is still good tho. That was a fun job. The old one was swollen so bad it would press against the bottom of the trackpad so it wouldn't click anymore.