Why are the events of the Gears of War 3 ending inconsistent with what happened earlier in the game?
Solution 1:
My interpretation of that is that Adam Fenix either exposed himself to a lower dose of the anti-lambent energy in the laboratory (he wasn't looking that good) or he exposed a biopsy of his tissue to the weapon in the lab. Either way, there would be no point to him fully exposing himself to the device if a successful test means he would die before finishing the weapon.