Uno Wont boot up stuck on starting

[Alanp]

I noticed my Uno flash memory was full after the box stopped responding as normal tried to reflash but it doesn't see the usb stick, Tried to restore to an earlier back up from image manager but this crashed the box now it wont boot and the led display is stuck on starting. Also I cant connect to my box anymore with DCC any ideas how I can reflash Thanks in advance