Send a pm to Fergusrb he may or may not be able to help you out. Its entirely up to him and I havent seen him about in a while. All the info you need can be found here or just buy a jtag kit.
You can buy the kit for around £15 plus P&P from the UK. It comes with instructions and all the files you need.
Might wait for fergie as i go on hols myself on sunday as its not mine just a friends, i wouldnt mind this is the 2nd time they have done this.
Are you sure it needs to be jtagged though, what did they do? And is there any thing on the LCD when you power it up?
Then it doesnt sound like it needs to be jtagged?? What does it say on the front display and if you can get into the menu post the system info please.
Now you have me confused in your first post you said the box had no power. And now you can read the system info???? Is your key emu on? Press menu, type 1570 on remote to find out,
Are you scanning from the direct feed, i.e. no splitter and you have the coax in the cable in socket . I presume you have a live feed? Press menu, factory settings, press OK. Unplug the box and then plug it back in and go through installation again.
Doesnt sound like a jtag problem, more like a tuner problem. Try a scan using the loopout socket underneath the cable in socket. After that I would suggest a reflash. But you can clone it from your box if you have "The Box" also just connect the two together via a null modem cable. I will tell you how, but try the scan through the loopout first and see how that goes.