Broken USRP report

USB interface seems ok:

when I connect the broken USRP, dmesg output is

usb 1-4: new high speed USB device using ehci_hcd and address 4
usb 1-4: configuration #1 chosen from 1 choice

when I disconnect it is:
usb 1-4: USB disconnect, address 4

what other tests can I run?

what does the led blinking actually mean?

thanks for help

vincenzo