you mentioned changing the port but did you try a different set of buds?

If they are available on the market I would venture to say that the screen will cost just about as much as buying a new TV. You may scout eBay,amazon or Craigslist for a used set that is identical to the one in question.

I can say with about 98% certainty that the new digitizer was not taped correctly at the bottom near the home button. If the tech did not get the whole bottom edge of the digitizer insulated it will act randomly. It is funny that it only happens in the small area but my money is on that area not being insulated.

Battery, charging port flex and the cellular antenna/speaker in closure have been changed with known good parts and no dice. It's down to a mobo problem. Does anyone know what chips to check for power management? We're is the pmu ic?

Im taking a shot in the dark here but sounds like a failed LCD or a loose connection. The only way to know for sure is to disassemble it and examine it for cable damage or loose connection and swap out lcd with a known good part to test theory.

Open it up and check if the LVDS (display data cable) is damaged or loose. Try a known good display data cable. If this fails replace the LCD.

disconnect the battery

Brand may be listed in about this apple. You will go to Apple menue, click the about this mac at the top of the drop down and click more info the system report then find SATA/SATA express on the list on the left. Buy fro OWC (macsales) they have their navigation set to compile a view of only drives compatible with your system. Hope this helps

I second the power cycle. Disconnect the battery or preform a hard reset to see if this remedies the issue.

The macbook pro has onboard gpu. There are options but you will have to get your hands dirty. Option one is to reflow the gpu on the logicboard. This can be achieved with a heat gun and patients. If you are unfamiliar with reflow i encourage you to check out the playstation yellow light of death fix guide and that method can be applied here too. Not a 100 percent fix but worth a try. Second is logicboard replacement. Oh wait, third would be GPU replacement but you will have to find someone that does chip level repair and is familiar with ball grid array soldering (i think it takes a special machine).