Seems like it’s quite the routine/regular error - I just assembled my A1; first BL printer w/high expectations, level-set) yet spent 4hrs - 4 hrs - (still) trying to resolve the errors while simply trying to calibrate…. Have had it for 3 days now, still not working and have tried everything the articles state, plus forum fix’s, removed the back plate of hot end to double check the posts - you name it - and of course the USBC cable - zero.
I’m not keeping this past another day or two if I can’t resolve this - am surprised as to how sensitive it must be re the precise placement of the build plate. Maybe decrease the tolerance somehow? Seems like a huge issue?
So after a lot of messing around, I resolved the issue. It is partly a known issue but only with early printers.
When you remove the rear panel, you can see a cable that goes from the circuit board to the heatbed. It is connected under the poop shute with a small harness clip attached to the bottom of the poop shute. The issue on early printers is that after a while, the cable cacthes on the poop shute and prevents the heat bed rising to its full height.This causes the Homing Z error and also in my case several warnings about sensor issues.
Simply pulling the cable (gently) so there is more cable on the heatbed side of the harness clip stops the problem. (At least until it works its way back and starts catching again).
FWIW I now leave the back panel off.so I dont have to keep removing it. I think it is likely I will buy a replacement panel and cut a suitable hole in the back so the cable can be adjusted without having to remove the panel each time.( And of course you can print a clip on door panel or something to fit in the gap )
(IIRC I remember seeing something that Bambu amended later models to not have this issue).
)