You need to format a SD Card in FAT, then name it "DREAMBOOT", and put it on the SD reader. Then turn on the box and it should stop during first steps of boot and you should be able to connect with Putty in COM mode to the service port. Using then the console to send all proper commands to restore the box.

But this to work, you should have the console/putty working, and this is why we asked you few times to check/be sure the console works on the service port... so try another PC as I am still very surprised that you have nothing on your Putty console during startup of box.

TS