I thought I found the solution but it was for a unibody MBP. So I removed the link but I did find a solution on my own. Just to let you all know, this is no means a proper fix. (1) Dissassemble top assembly from frame. (2) “Scrape" off the rubber gasket. (3) Get your new rubber gasket and cut off the part that is suppose to lay under the screen. (4) Test fit the new rubber gasket. (5) Use double sided adhesive to attach the bottom part of the gasket onto the assembly. (6) Use a bit of super glue then work your way around the sides and top. (7) Reassemble. I don't even recommend to do this at all to anybody. But I did it because my rubber gasket was damaged and was starting to fall apart. I don't know how long it will last. Could work for a while or it could fall out soon.
I know there’s a battery recall program for your model but I don’t know how Apple would handle your situation if you were to bring it in. Maybe they would reject it outright or give you a refurbished model. It may be worth a try.
You may have to find solder points on the logic board that gives the correct voltage to your tracker. It may be 3.3v or 5v. I don’t think you’ll find much info so I recommend looking at schematics (if you know how to read them) or use a multimeter to look for points that will give the correct voltage. Try to use points that are closely related to ac and battery power since I believe those are the best to draw additional current out of. Drawing current from points that lead to other components like the backlight, cpu, etc. may make the board malfunction. I don’t know anything about this on MBPs, I’m speaking from adding 12v led’s and 3.3v/5v glitch boards on Xbox 360s. Which is not the same as you’re trying to do.
Disconnect all the connectors for backlight and picture. Then try to turn your Mac on. This should help you troubleshoot and get down to what the problem is (lcd or logic board). And I have powered on my MBP w/o a screen attached before. With connecting a monitor via hdmi, I seen mine boot to the login screen.
I think its possible but I also think you will run into problems. Starting with the trackpad, the 2015 board is mean’t to be paired up with a force touch trackpad, which the 2013/2014 don’t have. Then the battery, the 2015 battery is different than the 2013/2014. And the LCD, I read that if a 2015 lcd pairs up with a 2013/2014 board, you will get picture but you won’t be able to control brightness. I expect the problem to be similar vice versa.