Firstly, don't be hard on yourself. You can take up Manipal exam again. And I suggest that you do. The highest score will be taken for ranking. About PESSAT, it changes every year. I suggest that you put your heart and soul into it, go though the all the topics mentioned by PES for PESSAT. It's better if you can read through all the topics in depth. We had an English section, too. If that's still exists, go though basic grammar. We had questions like 'What's the nearest meaning of ______?". Be prepared for the same.