To me, if it's not over or underwatering, it looks like she's got a lockout due to a nitrogen toxicity... since she's in flower, the nitrogen-heavy nutes should have been cut back to almost nothing and the bloom nutes added ... but if the grow nutes weren't cut back either sufficiently or at all, this could be the problem. Also would need to check the pH to make sure that's in the correct range... but yeah, you're right, without a diary it's awfully difficult to give advice with any degree of certainty... My money is on the nitrogen...
Good luck - have your friend join Grow Diaries here and start a diary even if s/he can only cobble together the last week of the grow... it would help tremendously.