New To Me Mid-2012 15" - Bluetooth Not Available

So, I’m about ready to throw in the towel on my beloved Mid-2012 MBP’s. This is #3 in a year and a half and I’m not particularly hard on my computers.

#1 was just sold.

#2 (Matte screen) was my baby, but has RAM module issues —> Kernel panics —> unreliable.

#3 (Glossy screen) was just purchased for $500 off of a grad student. Aside from some dust, the machine looks to be in great condition. When I tested it before purchase, everything worked, including Bluetooth. I can’t imagine that I wouldn’t have seen the Bluetooth Not Available icon. But alas…

I swapped out the optical drive, hard drive, and RAM from #3 for the SSD’s + RAM from #2. Three beeps. Tightented logic board, reseated the RAM, started up.

But, Bluetooth is not available. There is no Bluetooth in the System Preferences.

I deleted com.apple.bluetooth… plist files (there was no simply “bluetooth” file). I reset the SMC. I disconnected and reconnected: the battery, the bluetooth-to-logicboard cable, the antenna cables… and nothing.

My computer setup relies on bluetooth as I use a secondary monitor, keyboard, and mouse.

Thoughts? Is it as simple as, “time to troubleshoot and replace all the things”? If so, I think I’m throwing in the towel, selling both computers and getting a new MBP (though, they’re not without their problems… ugh).

Any thoughts?