10 min presentation so aim for about 10 slides. Follow the usual format (intro/background to put the work in context, methods, results, discussion/conclusions) but in your case, I would concentrate on the methodology and trouble-shooting. It's a great opportunity for you to demonstrate your trouble-shooting skills and your perseverance in the face of adversity and they are must-have skills for any prospective PhD student! Practice your presentation until you are really comfortable with it and if you can, get feedback from your friends/peers/academics/anyone who will listen. Try to think of any obvious questions they might ask about the work so you can prepare possible answers. Best of luck, you can do it!