Inspiron 5567 External Ports Not Functioning

Apologies in advance for the book I am about to write, but I want to cover everything that has transpired on this laptop.

My Inspiron 5567 has a noisy heat sink fan. I opened it up to troubleshoot. In my attempt to examine the fan, I removed the heat sink, but when it was assembled, the On/Off switch ribbon was glued to the fan housing.
So I ended up yanking that out of its connector. To restore the ribbon, I needed to pull up the motherboard. To do that, I had to disconnect the display cable. Fixed the on/off ribbon, put everything back to its place and....the front LED displayed 2 amber, 7 white blinks indicating I broke the display somehow. OK, bought a replacement display assembly. Before fully installing, I connected the replacement assembly up to make sure it turns on. I booted up the machine, got to windows on the new display, life is good.
I actually install the display, route the cable, and it wouldnt run off the display. What happened when I booted up is I get the Dell logo on the display, which is followed by darkness. 

I could use the laptop by hooking up an external display through the HDMI port

I went through the diagnostic tool (F12) at power on and did see the color test pattern on the laptop display. 

I used F2 on power up to get to another set of display settings (which can be seen on the laptop display, but admittedly dont know what to do next, there, if anything)

I tried updating every driver in Windows I can think of that has something to do with the display. 

All to no avail. THEN, I replaced the back cover and out of nowhere, the main screen is working again, for seemingly no reason.

NOW, however, I can't extend the desktop with the external monitor. The external monitor is no longer listed as an external device in hardware manager!

Further, I can't get my USB interfaces to recognize externaly connected mice (wired or wireless). The only USB device I can connect through is an SD card via a usb interconnect.

And the built in camera is not longer recognized either, for what its worth.

I have no idea what is going on, why I seem to fix one problem only to have a brand new one pop up. Any ideas on what to try?