I replaced a broken 1440x900 LCD display with a 1680x1050 LCD from laptopscreen.com. Screen works great except for this...

I have done this with a 2010 Macbook Pro 15", and although the high res screen works perfectly, I do have one problem I would love help with. 1. The new high res screen fits perfectly and interfaces with the existing LVDS cable. 2. The problem is that the screen stays dark at bootup until very late in the bootup process. Basically the screen comes on just as the desktop appears. You never see the grey Apple startup screen. The problem is that now I can't see the Startup Manager screen (option key at startup), single user mode, or Target Disk Mode. I have tried a clean install on a repartitioned disk of OSX 10.9 but it has not resolved this problem. Tried resetting NVRAM and the Power Manager, no change.