Make sure latest VEXos
& look at VEX IQ brain stuck in DFU
& Cannot connect to Vex IQ Brain
And there is this VEX IQ Brain Problem which (like everything) may be out-of-date…
In Computer refusing to do anything with VEX IQ Brain there is discussion of COM ports which helped me with your first issue.
& Brains Not Communicating with Computers
I will quote myself (!):
Finally, especially about your second issue if not solved above: