DSi XL wont turn on

Mike if your DSi XL worked, besides the bad upper screen, prior to you replacing the screen then one of your cables is either not seated properly or was broken internally during the repair. If it is a problem with a cable not being seated properly the chances are it is a ribbon cable going to one of the screens is sitting slightly of kilter, not in far enough or the flap on the socket is not sitting flat and even. Those flaps like to bow in the center sometimes. Please disassemble and put it back together again double checking all connections. Use a magnifying glass to be sure the cables are in their sockets even and square to the socket. If during your repair you compromised one of the cables it is more than likely the one to your new LCD that goes through the hinge. If such is the case you will need to replace it we have then here. Here is a guide for installing the upper LCD.