Don't even think about re flashing if you're a first time user of a borrowed Iliad...
The official way to reset the pin code is via your 'my irex' account.
https://myirex.irexnet.com/user.php
You will need the mac-address (written on the back of the Iliad)
I'm not sure if you will be able to create and activate a 'my irex' account without access to your Iliad...
HTH, Hansel