By Adrian Kingsley-Hughes | January 16, 2012, 2:08pm PST Summary: Unknown serial number problem preventing ICS installation. Trying to get Android 4.0 Ice Cream Sandwich onto your shiny new ASUS Transformer Prime tablet but seeing it fail because of an unknown serial number problem? Youre not alone. The Ice Cream Sandwich update was released for the Transformer Prime last week, but some users are unable to install the much-awaited update because their tablets are showing an unknown serial number under the About tablet menu. ASUS support representative Gary Key posted this possible solution over on the XDA-Developers forum that might be worth a try, but given the feedback I wouldnt hold my breath: As for the Serial Number Unknown problem, please try doing a factory reset. If it does not work the first time, after the reboot, please try it again and once at the desktop, wait about 10~15 minutes for the system to sync with the server. So far this has worked for users I am directly assisting at the moment on another forum but it has not worked on two particular units that were returned yesterday. If this doesnt help, youll have to wait for a better fix from ASUS.