I don't even really remember the bleeding process so I'm sure it was pretty straightforward. It's also an electric pump and relatively small lines, so I think the coolant speed is both constant and high, which helps.
I collected all the coolant that I drained quite carefully, which let me be pretty confident there were no huge bubbles in the system providing I could get it all back into the loop. I think I spilled about 1/2 a cup or so during the process, so I wasn't expecting perfection. I also think I went through the bleeding process relatively quickly and then just left the car in 'ready' mode for a couple of hours to clear any bubbles.
On the positive side, the worst case load into the cooling system for the on-board charger is 400-500W, which is pretty solidly nothing for cooling power electronics. Most of that is coming from a single huge module in the charger too, which helps a lot.
The 2011 service manual has the procedure listed in the 'HCO - High Voltage Cooling' section.
https://ownersmanuals2.com/nissan/leaf- ... -hco-43099
Page 9 has draining and refilling.
But the manual basically says:
There's a bleeder plug on the bottom side of the on-board charger, next to where the coolant inlet/outlet are. Remove that.
Completely fill the degas tank.
Remove the joint in the coolant hose at the 'traction inverter front', which is the hose closest the hood at the very front of the engine bay (motor bay? under-hood area?). Visually check for water flow and reconnect, which I'm guessing means 'does any leak out'.
Refill degas tank.
Close the bleeder plug on the charger and close the degas tank cap. I vaguely remember coolant trickling out a little at this point.
Start the car into 'ready' mode (foot on the brake, press power button, car should chime and come on with a green car icon with arrows under it on the dash, this is the 'ready to drive' mode which has the HV active) which turns on the pumps.
Watch the level in the degas tank and refill as it lowers.
Once the level has stopped falling, close the cap and turn the car off. Turning the car off with the cap open may cause coolant to surge out of the cap.
From there, it's basically make everything quiet, turn the car on and run the pumps for a minute, checking to see whether you hear gurgling from the back of the car. If so, there's still air and let it continue to bleed.
Hopefully that helps. Seems like you might have gotten a sweet deal for what is hopefully very little extra effort!
I've actually been discussing the possibility of repairing the ZE0 on-board chargers as they seem like a 'common' enough fault that, here in NZ at least, getting replacements out of wrecked vehicles is only just keeping up with demand. Still not anything to worry about, but definitely one of the more common faults. Maybe as many as 1% of cars having it happen in their lifespan, I'd hazard a guess?