my fan went out after about 1500 hours printing and support sent me a replacement fan. I painstakingly spent hours slowly taking it apart and then back together with the new fan only for it to immediately fail to move the filament block. At this point it just clicks a few times and errors. It seems like it would be related to me probably having to repair the fan but so far the obvious things are plugged correctly, I also physically cannot move the blocker more than halfway ish, not real sure if that means anything, Am I stuck removing and reinstalling it all again? It was incredibly difficult for me so I would like to avoid it if I can, any feedback is appreciated, even if it’s the hard truth to break it all down again 
wish I knew enough about the electronics and mechanism to know if I crossed a specific wire or something.
You have to go back in there.
My guess is the one of the ribbon cables is not inserted far enough.
The Bambu Wiki does detail what each connector is for…
I am sorry you had to go through that — taking the toolhead apart is definitely not a fun job.
If you physically cannot move the filament blocker through its full travel by hand, I would probably look at the mechanical side first rather than the electronics. The clicking sounds like the motor is trying to move it, but something may be binding, misaligned, or not seated correctly.
I have replaced the hotend cooling fan six times on my H2D since I got the machine, and it looks like the current one may be on its way out again, so I have had the whole toolhead apart a few times too. 
A bad connection or crossed wire could of course cause errors, but I would not normally expect that to prevent the blocker from moving freely by hand. Before tearing it all down again, I would carefully check that nothing is pinched, the blocker is aligned correctly, the spring/lever is seated properly, and that no screws are slightly over-tightened or in the wrong position.
Unfortunately, if it still cannot move smoothly by hand, it may need to come apart again. I know that is probably the last thing you wanted to hear, but if the mechanism is physically binding, the printer will likely keep clicking and throwing errors until that bind is fixed.
Thank you. I’ll just have to do it, no real choice. Any tips on making the break down and set back up better? My biggest issues are really seeing the electronics and my giant hotdog fingers - even with tweezers I really struggle to get these in the right spots but I think I will have to move the entire Pinter down to a shorter table and turn it around. Working from the front made everything about 90% worse. Current me would certainly tell past me to just remove the Panda perch and AMS systems from the top - not worth the hassle it added to use my phone to see behind the print head. I also noticed the H2D guide is a bit lacking on some of the connectors…I want to say 2 of them were very unclear as to which went into the city spots, I distinctly recall all the photos being already unhooked. This time I’ll try not to keep working on it until 3 am
Flipped it around when I got home and it’s like 9 billion percent easier to work with lesson learned for sure. Think I might get rid of this panda perch at some point if it needs as much repair as it sounds like it might. Anyway I backed off the fan screws a little and the blocker immediately started working by hand, I’ll have to see what wire is trapped where or if I just tightened them so much it pushed it just enough.
Just sad I got the cords plugged technically right but failed at not pinching the cords I guess
For anyone who cares it was an improper seating of the motor cover blocking the tool. Unfortunately I now caught a new problem which is the part cooling fan running at 100% as soon as I turn on the printer
If the part cooling fan runs at 100% as soon as the printer is powered on, it could be a faulty sensor, or possibly a connector/board issue related to the replacement. I would recommend checking with support just to be on the safe side.
The fan definitely should not be running at 100% constantly, so it sounds like something needs to be looked at. It is a bit unfortunate though, because if this is considered a consumable part, it would be nice if it were easier to access and replace without risking additional issues.
I enjoy my method of changing the fan without disassembly. Just too many points of failure with Bambu’s method.