open
Do not replace the mainboard if you have not tried replacing this part yet: http://www.ebay.com.au/itm/Original-Samsung-GT-I9515-Galaxy-S4-Sim-Micro-SD-Kartenleser-Card-Reader-Flex-/131596675774?hash=item1ea3c5eabe:g:TowAAOSw0HVWDkpr