I don't understand this.
The lcd/touch screen are attached to a front frame. You can buy the lcd and screen with or w/o the frame. If you buy it w/o it is much more work, as you need to remove the possible cracked screen and will most likely damage the lcd in doing so. This is ok though as now you can replace both onto the old frame and reassemble the phone.
If you purchased the lcd and screen assembled on a front frame, they come as described...( ASSEMBLED).
Now all you need to do is pass the multiwire connector on the new front assembly through the rear assembly and snap on the wire connecter gently . You may want to place the 2 halves side by side and plug in the connector before fully assembling to make sure the new and old equipment are working. The rear assembly faces up and the front assembly will be on the right and facing down. Reinstall the bottom rear charger/home button cover and charged battery. The on button is on the left side of the rear assembly, a very small white switch. Use a non metallic (plastic) tool to press in the switch, holding until you feel the phone vibrate. The screen should come on shortly after, and you may try a few functions.
The Mother board is on the rear assembly and does not need to be moved in either situation. I understand that the front frame is different between models . The GT I9500 front frame is not compatble with GT-I9505.
The GT-I9505 is compatible with the the Sprint model SPH-L720T, but not with the L720 ;
the Verizon model # SCH-1545, and the US Cellular model # SCH-R970.
The AT&T model SGH-1337 is compatible with the T- Mobil model SGH_M919
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