How do I fix an x-pm brother 4000d error

What size/capacity USB stick? Some machines will not read the larger ones.

This is a pulse motor failure. You cannot fix this without testing mainboard and Pulse motor. Take it to a mechanic. Sorry for the bad news

question is unclear. I had one of these super nice machines and it's one of the most advanced "auto-thread" mechanisms in any machine.
Go to an authorized Brother Repair shop and have it tuned- up and get more advice on how you might be able to DIY???

try unplugging it and letting it rest for 20 minutes? Sometimes that will reboot it.

try changing the needle
clean under the needle plate & in the bobbin area for loose threads or lint
rethread the machine top & bobbin

Try sewvacdoctor.com for list of possible remedies. Jimmy

yes, it's possible that it's the motherboard & needs to be serviced

You probably need to take it in for service. Thread guide pulse motor (TG-PM) is jammed with thread. There is a new shield that that can install to keep this from happening again.
You can gently try to move it with the machine on and see if that works, it is the little shuttle that goes up and down on the front of the machine, it is probably stuck where you can see it.
good luck!