Need help!!! Cruze 2.0l LTZ Auto having glow plug problem and comms code error

Guys,

Need urgent help! It all started when I was at a stop signal and my car jerked a few times and the glow lamp signal came on the dashboard when the car jerked. I had driven for 7 odd kms, so would imagine that the car was at optimal temperature and no signal was being sent to glow lamps. After two jerks, the car shut down but started right back. Drove for a few meters and took a stop over. After like 5 mins, tried starting the car but it won't! The engine would not even crank, and the immobilizer signal showed on the dashboard. Tried pushing the start button a few times, and the engine started.

It doesn't end here, I drove for a few kms and the car again broke down. Only this time the car would not start after repeated attempts. I have a video but not able to upload it, but it was like everything else was working (headlight, stereo, cabin lights). When I pushed the start button the dashboard lights would come on and then off, the needles would move but nothing. Nothing in the engine at all, it was totally dead. After 10 mins of fidgeting with the start button the car started and I drove off to home. I drove for around 9 kms, with just one jerk on a stop light but reached home safe.

Next day I sent the car to the dealer, he screened the car and told me of the OBD codes. The car recorded these codes - U0100, P2510-59, P051300, P0683. THE DEALER IS RECOMMENDING THAT THE ENTIRE ENGINE WIRING HARNESS BE REPLACED! COST ESTIMATE $900!

I'm a novice but I think that the dealer is being premature in his recommendation. But not sure what my next steps should be.

Please help guys, I just bought this pre-worshipped cruze 3 months back and I'm sweating it off.

P.S. Is there any way I can upload videos to my thread?