If they fired you within two weeks, they're most likely the problem, rather than you. I mean - if they expect you to be 100% productive within your first few weeks, they're in cloud-cuckoo-land. We allow a three month probationary period at 80% of full salary for us to mutually get to know each other and for the new starter to get up to speed - and then, and only then, do we assess performance. If it's bad - you're out, if it's good, you're in - but two weeks isn't a fair sample.