Illumina Process Development Engineer (Reagent) interview questions

I applied through Illumina website and got an email soon later. First was phone interview via Hirevue, next I was called to on-site interview with a manager and another senior engineer. At that time, the impression that I received was that they really needed people urgently to fill up that position. First 20 mins was all about background and interest sort of questions, the unexpected part was when they tested me to troubleshoot for the faulty product (real-life example) on the spot. Now when I looked back, that test wasn't that difficult at all, but I was too nervous due to the stressful face I saw from one of them (perhaps this was one of the test as well! Don't get scared by their look) that I couldn't think logically. So that was obvious that I couldn't get any offer in the end.