I took photos as I went through the process, but there wasn't much that I followed, since this error is not well documented. You could look up videos with tips for chip removal, but it's something that really takes practice. I had some clues that the RAM was the issue, such as this case often being linked to RAM not installed properly with mod chips, and the fact that things worked briefly, and even the display attempted to start at some points.
As for performing the fix, I'd highly recommend only doing this if you're very comfortable with surface mount soldering, and more importantly surface mount desoldering. You can do a lot of damage to the board/pads if you're not careful removing the RAM chips. I'd also recommend using a decent quality microscope when doing this, so you can make sure everything is cleanly performed (last thing you want is a bridge or disconnected connection that continues to give you headaches). I've been doing this sort of work for a long time, and even I made a few mistakes (thankfully I knew how to fix them). There are tools like chip quik, which would make the removal of the old RAM a lot easier, but that still requires a decent amount of comfort using a soldering iron to do surface mount level work. I would not recommend attempting this with just a hot air gun, there are just too many small passive components around the RAM that could easily be blown off.
After U6D1 was removed (notice I ended up losing a pad due to human error):
After soldering a new RAM chip for U6D1 (was able to fix the pad issue with a little rework):