This page contains spoilers about the Heartbound ARG. If you want to solve the puzzle yourself, avoid reading this article.
As this is the beginning of Phase 2, the first task is to actually find the trailhead. Entering the code does that has been found at the end of Phase 1 does something more than translating the Guardian Glyphs.
Finding the Trailhead
When you type the code into the game, it drops a new file next to your save file, wherever that happens to be. This file can be found at the following locations:
SeeMeSayMe.thor won't render with any normal program. It's encoded. Fortunately the encoding is an easy one. The double-equals (==) at the end is a dead-giveaway.
There are many ways to decode such files and one of them is the online Base64 to image converter, in which you will have to paste the file contents and it will decode the file to an image. Make sure you don't have to copy-paste the result. That will almost certainly corrupt the resulting file. Find a place where you can download the resulting file.
This puzzle is a reprise of an earlier puzzle Thor wrote: Play Rude
As if that wasn't obscure enough, we don't have a normal cipher text. Instead we have clusters like NNIII. To decode that, we have to look for N in square 2, and I in square 3, and cross-reference to get DI.
Which gives us the string: DI AN RF KL SU IE DN EC RE
If rendered vertically, like the Play Rude puzzle suggests:
DI AN RF KL SU IE DN EC RE
You`ll get "DARKSIDERINFLUENCE". Since this is Phase 2, and we're starting over, put that right in the URL right after "Heartbound/", and you'll get the Pact page.