They asked me to fill up my particulars. Then they interviewed me, asking for my experience, and they mentioned they would contact me shortly. I received confirmation in less than a week.

Just briefing you the jobscope and asking you which field you want to go to. Got an offer a week later but they rescinded the offer after two hours. When ask for a reasons, they only state they decided to go for another candidate. Imagine you already resign from your job after you were given an offer just to be told they "RETRACTED" their offer. If they can change people very fast, what more they can do once you actually join the company.