Cluster %^&* What did I do??

[Jerinoid]

2007 E61 530XiT. Car is in great shape - 136,350 miles. Drove it into my garage yesterday - everything working perfect but time to clear the Sunroof drains which seemed to NOT be draining. There was NO Water in the Battery or spare tire bays but I noticed some wet in there after the last rain 2 weeks ago, which I dried out. I take off the D-Pillar trims and perform the drain maintenance as prescribed (cut the drain lines and replaced them w/new clear tubing from the 2 outlets in the back of the sunroof down to middle of D-Pillar). After I finish (but before replacing D-Pillar trim and buttoning everything back up) when I go to start the car to open the sunroof, I find ALL THE WARNING LIGHTS are illuminated, the iDrive screen is black and won't boot up, and most electrical features (power seats, windows, remote lock, seat heaters, etc.) do NOT work, however the car will start (but it requires pressing the start button 2x) and actually drives just fine (took it out for 30 minutes to diagnose), lights, turn signals, and all basic functionality is fine. Power steering seems tight though. I disconnected negative battery cable for about 30 minutes to try and reset DME, but everything is the same on reconnect. The ONLY electrical I messed with while replacing the drains was that I disconnected the large wiring harness plug in the fusebox to check if there was any corrosion from moisture on the leads/terminals and reconnected it. Car was off when I did that but it seemed to hiccup when I pulled that big plug out. While running, the Center BC display cycles through all warnings (4x4, TPMS, Service, ABS, etc.) continuiously. I'm sure this is probably some kind of basic reset issue, or maybe IBS?? Any thoughts? Pic shows the state of the cluster while the car is running.

[Jerinoid]

UPDATE: For future reference - I've found that THIS was the culprit. I pulled out this wiring harness plug/connector from the fusebox in the passenger-rear battery bay of the car and apparently didn't push it back in all the way. Once re-connected with force, all the pins made contact and the car lit up as it is supposed to with everything back to normal again.