Recently I found a hole in my gearbox. To repair the hold, the mechanic pulled the engine. During that exercise he broke the drive train but that was replaced (this is mainly to show the lack of care he took). When the hole was welded and the engine replaced, the electrician rewired the car. Once that was done, the car would not start although everything was working before the mechanic started working. I had the electrician recheck and test everything and all electronics are working. Since the original mechanic refused to do anymore work on the car, I had another mechanic check it. He says that the lower crankshaft is weak. He suggests that I change from fuel injection to carburation. I fail to understand why the car is not working since it was prior to repairing the gearbox leak. Please advise me as to what happened and what I should do about it.