htc nexus 9 unlock boot loader

my htc nexux 9 stuck I can get bootloader I need flash this tablet I got 2 different y-cable and 2 usb sd reder when I connect to pc they both working xtcclip2 software I cant get unlock boot loader read guide from xtcclip2 website how to use y-cable connect y-cable to tablet and fastboot and simlock still not connect clip on tablet please help where iam doing mistakes