volleysi

Hi, I hope someone can help, I have a 4.7 Cherokee 2000. Nice motor just a lot of fuel stops, lol. The problem I have is I was jump started after the battery went flat ( left the lights on) (**** I know). A kind gentleman stopped and used jump leads to start me. I connected them up. I started the jeep, but he disconnected the leads straight away and she died again. It's a new battery but very flat, I'm guessing it was because it was so flat and just using the throttle drained to much power. He reconnected, but spiked it and sparked, against my battery.
I now have no speedo or rev counter, is problem likely to be in the ecu, the back of the speedo or a relay, I can't seem to find a fuse that just covers the rev counter and speedo. It's been a few days now and everything else seems ok. The only thing I haven't tried yet is disconnecting the battery for a while and maybe that will reboot them. Long shot I know, anyone else had this problem ??