I just received a BigTreeTech BiQu BX printer that has a rPi integrated running OctoBTT.
I can connect from my PC to the Octo Server running on the printer, but I cannot connect to the printer itself to control it from my PC using OctoPi.
Any ideas here?
Thanks.
logs please 
I don't know that printer. Is there a separate power supply for printer and pi or does the pi start up as soon as you turn the printer on?
The BiQu BX is a printer made be BigTreeTech. They use their control board paired with a nice 7" touchscreen. The Pi is mounted right to the back of the touchscreen controller and uses OctoBTT as a control interface on the touchscreen. OctoBtt is similar to OctoDash, it is a modified Octoprint interface. To install this one has to actually download the Octoprint image first, start it up and "update" with some BTT code that provides the user interface on the touchscreen.
The Pi does run the Octoprint server, as I can connect to that, but they must use some other type of interface to actually communicate with the printer. They actually state that the serial port is disabled.
I am just not sure what good this does if I cannot connect via a web interface, which to me is the main objective of Octoprint.
Ok then I guess you got two different power supplies?
Make sure that you turn on both - the Pi and the printer.
alright. well then you have to connect the pi via usb to the printer 
That did it, though nowhere mentioned in the instructions. It appears that the maker did indeed disable the board internal serial port and an external serial connection to the main board on the printer is required. Of course nowhere any mention in the manual.
Thanks for pointing in the right direction.