2009 M35 RWD HR engine.
I went into the M35 and started it up. It's being driven 2-3 days per week on average. No warning lights, no issues starting, no electronic issues ever until today. I started the car - started normally and 2 seconds later, the passenger window put itself all the way down. Neither the driver switch or passenger door switch will raise it back up. All other windows operate normally by door switched or driver's door. Sunroof, both front and rear eats, sun shade, and both mirrors all operate normally. The passenger window motor makes no noise so I reckon it blew, but why did it open itself before dying? It's a head scratcher. Any ideas?
Is there a way to manually raise it so I can unplug that motor and replace it with new?

The window switches are all on a LIN link, but if a switch fails and reads "down" all the time it will override any LIN inputs from the Master Switch. So I'd say it's most likely a bad switch at the bad window. The only way to get it up will be to pop out the switch and then jump power and ground manually to the window motor from the switch connector. There will be a fat blue and green set of wires at one end of the switch connector, those are the motor wires. Jump power to blue and ground to green and the window should roll up. Then just leave the switch disconnected.

Thank you for that! I also noticed the next day it DID roll up with the driver switch and the passenger door switch. However, the driver's door will only roll it up, not down. I'm thinking used driver switch assembly and used passenger switch. I already ordered a new motor from Infiniti just to add to my spare parts collection. I removed the passenger door panel and unplugged the motor so it can't misbehave while i wait on parts. That way, regardless of what is making it roll down, I disabled the motor.

You're most welcome! Post the fix when the parts come in so we all know what actually failed.

UPDATE: Master driver door switches from Infiniti: $681, used from Ebay: $68
Passenger door window switch from Infiniti: $214, used from Ebay: $36
Window motor from Infiniti: $354, Used from Ebay: $45
No warranty on these items, but $1,249 Vs $172 (with shipping) ... do I even care?

I'd certainly try a used one first, except for the motor. You can probably get that aftermarket new.