Complex sentence: She denied that it affected her performance in the presentation, but Lord Sugar was unhappy with her explanation, despite being impressed with her performance in the previous task and warned her that she only narrowly avoided firing due to Aisha being most responsible for the loss.
Split into simpler sentences: She denied that it affected her performance in the presentation, but Lord Sugar was unhappy with her explanation. Despite being impressed with her performance in the previous task, he warned her that she only narrowly avoided being fired due to Aisha being the most responsible for the loss.