Ok, here's the story.
I got the XV Tuner cable a few weeks ago, and when I initially got it it wouldn't communicate with the bike. Key on, key off, whatever - didn't matter. I sent Kurt an email about it, but before I got a response it started working - I didn't do anything different, didn't unplug it, didn't move the ground - nothing. From the get-go my 12V power supply was connected to the battery to prevent the voltage dropping (I'm a Porsche/Ferrari/Mercedes technician by trade, so I used SOP for flashing an ECM/ECU), so it wasn't a matter of the voltage fluctuating.
Cable started working, seemed to work great. Took the bike to a dyno, mapped it with the Alice map, made a pull, and it did great. After a few runs and playing with a few different maps and adjusting the fuel offset, the 450 put down 52hp/67tq. I was pretty happy with that, so I decided to make one more pull and call it a day. I had XV Tuner connected and was monitoring the 'live data' feed, and went to make another pull. About halfway through the run, the bike started running crazy rich, then backfired and shut off. The XV Tuner display showed 'connecting to ECU' in the top right corner, the green light wasn't flashing, and it didn't show any more live data or any connection. Just after that, I noticed fuel running down the side of the engine casing - popped up the tank, and the injectors were STILL dumping fuel into the throttle bodies, so much so that the throttle bodies were full of fuel and overflowing. After that, I couldn't get XV tuner to communicate with the ECU, and the bike wouldn't power on - key on, no power to the fuel pump, nothing. I didn't try to turn it over because the cylinders were still full of fuel.
I yanked the motor and tore it down, as I was certain when it hydrolocked it bent something. For the most part, everything seemed ok, although it killed both headgaskets. Got parts from Ted at AF1 and they were here a few days ago, spent yesterday tearing down the motor and today putting it back together.
Got the motor back in the bike, and I'm back where I was before, only without a hydrolocked motor - bike will power up but won't power on the fuel pump, and XV Tuner sits infinitely flashing the red light at me and telling me 'connecting to ECU'. All fuses are good, and as I type this my printer is spitting out the giant BMP wiring diagram that's posted on here.
edit: Just an update, went over all the wiring per the information in Jim Hubert's 'High-Resolution Wiring Diagram, ECU Pinout, Circuit Descriptions' thread. Everything external to the ECU is ok. The ECU is seeing switched power with the key at pin 8, all grounds are present at the ECU connector, however the ECU is not sending any outputs - no power to the fuel pump, and no communication with the XV Tuner software.
edit 2: Problem has been resolved. Not sure what caused it, but it's fixed now.