I call upon the MacRumors Sages! I am recovering a friend's MacBook Pro 13" Late 2011 MD313LL/A damaged by spilled water. It is out of warranty so anything goes. As soon as I opened the water damaged MD313LL/A I found the Logic Board badly corroded and knew it needed to be replaced. I purchased a MC724LL/A for parts to repair the MD313LL/A (on eBay reporting fixable issues). I tested the MC724LL/A and found it Option booted to Internet Recovery, but would not complete the process due to a bad hard drive. The Hard drive from the MD313LL/A did successfully boot without issues. That would solve the problem except for the broken right hinge mounting point on the screen and the dented mid-body just to the right of the Trackpad, making it impossible to click even though the cursor moved (issues not clear in listing). I subsequently used this track pad successfully in the body of the MD313LL/A, replacing the water damaged one there that did not work. I proceeded to replace the parts one at a time starting with the LB. I immediately discovered the LCD did not work and I had no video at all. I had a Thunderbolt External Video Adapter for external display. I purchased a replacement LCD display and after connected, I now had external video, but the MacBook Pro display still did not work. I also did not have working speakers. I performed a PRAM reset that restored audio, but now I no longer had keyboard backlight. I still considered that a win. I did not lose external video with this PRAM reset. I continued replacing parts one at a time, but at each step I could only get to a Gray Screen with nothing else. I continued replacing parts one at a time without joy. After I replaced all the parts from the damaged MC724LL/A into the perfect body of the MD313LL/A and still could only get the Gray Screen I tried a second PRAM reset. This time I lost the external video. I have tried disconnecting the battery, SMC resets and numerous PRAM resets with no joy. What can I do now? Did the LB fail? Did I somehow brick the LB? I hope there is a Wise Mac Rumors Forum Member out there that can lead me around this to finish the job or tell me it is hopeless and for me to move on. I also have USB Flash Drives with Lion and Yosemite on them that I used along the way as well, but they nor Internet Recovery would get me beyond the blank Gray Screen. On my first test of the MC724LL/A Internet Recovery, the MacBook Pro went a menu to reformat the disk, reload Lion and other choices after loading the initial interface, so I know what it should do for Internet Recovery after downloading the initial interface. Also, is there any way to test the LCD screen? I only have the word of the guy I bought the LCD screen assembly from that it works. I knew something was wrong with the original MD313LL/A LCD screen as there was no external video until I replaced it. MacRumors is great! I could not have gotten this far without the information in the Forum here. I just hope there is some Wise person out there to take me home or tell me to move on as the issue cannot be fixed. Thank you all in advance!