USB connection is not available (there is a port COM)

1.Possible cause analysis of failure:
a. Whether the “device port” at the lower right corner of the software is selected correctly (USB and network).
b. The USB drive is not installed when installing the software for the first time.
Move, and then install the operating software
c. The port does not correspond, change the port again (e.g. COM5
Change COM3).
d. Control motherboard hardware if there is no U43
(LJ245A) cannot be upgraded to a special version.
e. Control the main board hardware if there is U43
(LJ245A) The upgrade cannot be upgraded to before 5.0.21.
2.Solution:If it is a version upgrade error, re-enter the program.