I met the same problem after firmware updating, but in my case everything is more complicated . As described above, I tried to switch the device to the DFU mode, LED's show me that the device is in DFU mode (LED1 is constantly ON), but windows device manager still says "Unknown USB device(Device descriptor request failed)", and of course I did not find the device on the network. Using USB-COM adapter i connected to JTAGUART and saw the following:
U-Boot PlutoSDR v0.20-PlutoSDR-00053-g89d0754 (May 28 2019 - 19:24:22 -0700)
I2C: ready
DRAM: ECC disabled 512 MiB
SF: Detected N25Q256A with page size 256 Bytes, erase size 4 KiB, total 32 MiB
In: serial@e0001000
Out: serial@e0001000
Err: serial@e0001000
Model: Zynq Pluto SDR Board
Hit any key to stop autoboot: 0
Unknown command 'bootp' - try 'help'
Wrong Image Format for bootm command
ERROR: can't get kernel image!
Pluto>
I tried to find out what was wrong with the USB port, I got the following:
Pluto> usb info
USB is stopped. Please issue 'usb start' first.
Pluto> usb start
starting USB...
USB0: ULPI request timed out
zynq ULPI viewport init failed
lowlevel init failed
USB1: usb1 wrong num MIO: 0, Index 1
lowlevel init failed
USB error: all controllers failed lowlevel init
Pluto>
I don't think the port has burned out. I think I made a mistake when updating firmware. How can I restore firmware using JTAGUART?