This happened to me too. You should replace the hex-values instead of the text-string.
1. Press ctrl + r to open the replace window.
2. Search for: 49 53 4C 4F 43 4B 45 44 20 54 52 55 45
3. Replace with: 49 53 4C 4F 43 4B 45 44 20 46 41 4C 53 45
4. Datatype: hex-values.
5. Click replace all.
6. Save and start the game.
49 53 4C 4F 43 4B 45 44 20 46 41 4C 53 45 (ISLOCKED FALSE)
49 53 4C 4F 43 4B 45 44 20 54 52 55 45 (ISLOCKED TRUE)
Doesnt work D: Thanks anyway!
Try to replace this one: 49 53 4C 4F 43 4B 45 44 20 54 52 55 45 0D (ISLOCKED TRUE)
I forgot the "0D" at the end of the code.
EDIT: Yeah this is the corret hex-value, I tested it myself and worked.
You have to start a new game to unlock all the doors with this replace method. Just pause the game and select "restart" and don't worry, your progress won't be lost (unless you overwrite your original save file).