Ok, so I've gone to the mages tower after Flems hut, read a book that I've translated, and met the dorky mage. When I go to the repository with the sentinals that are 'acting strangely' I cannot kill them (all hits/spells produce 0 damage) and now that I mention it they cannot kill me either. I've tried the following:
1. Loading a previous save 2. Trying a different character 3. Starting a new game with new character 4. Disabling all DLC (except WH, obviously) 5. Erasing all DLC in "override" folder 6. Restarting DA and my computer 7. All combo of spells 8. "runscript killallhostiles" 9. The 'damge health' function on the trainer 10. not loading the trainer.
As I said, the Sentinels health bar stays at full when you use the damage health cheat on the trainer - you can lower the players health to next to nothing with the cheat, but he/she won't die either.
Please help, I just want to complete this *1^%&$£ mission!!!