Beagle Board modification

I was wondering if i added a header to the I/O pins would i still be
able to return it or would that void the warranty? i ask because i
would like to add on the lcd screen and the only way i can thing of
making the connection would be to put in a header to connect the 2


You can add the connector, but, if it is found that you did a bad soldering job and it causes damage to the board, that could be an issue. Adding the connecotr correcxtly does not void th eewaaranty, but sending high voltages into the pins could. So, you need to be careful.