We’ve just had an email from one of our distributors:
I have noticed an increase in the quantity of returns where it’s claimed by the customer that the Pi will not boot. My view is that in the majority of instances they are attempting to use the unit with an OS that is not compatible with the Hynix chip, often inserting a card from a Pi they already have which reinforces the view in their mind that the new unit is faulty.
Just yesterday I received a batch of 21 units from a school and upon testing with the latest version of Raspbian Wheezy all booted normally.
If your 512MB Pi has a Hynix memory chip in the middle of the board (that’s the black, square RAM chip right in the centre, and it’ll either say Samsung or Hynix on it in white letters), please ensure you are using the latest version of Raspbian, which you can get from the downloads link at the top of the page. The version on that page will always be the latest available. It seems a lot of the people who have been caught out by this are folk who have bought a pre-flashed card from someone on eBay or Amazon. We always recommend against this, because the images on those grey-market cards are often months out of date – and a lot of work is done on the software every week, so a months-old operating system will bear little resemblance to the newest version. If you absolutely must buy a pre-loaded SD card, make sure you buy it from a reputable source.