Sorry for the necropost, but just came across this thread. Lots of useful information in the Spreadsheet on Page 3. If anyone is still alive and stuck on this game, I'll do my best to help.
Warning - Key is at the end of the Forrest Ruins. Straight path, easy to find.
Nabraham - You can activate the buttons from any side, not just the front. Active them from the side
Amkight - It is a straight shot, should be easy to get the end. Where are you stuck?
Just beat the Phoenixes with ~lvl 110 characters. Not too difficult using a strategy. On the second playthrough, going for <100 level for a good challenge.