i just bought a 2000 new beetle GLS with turbo engine. the engine had to be rebuilt. it ran for a while but was making a rattle noise. When fixed the car refuses to start. Mechanic is a friend of mine and told me he tried anything but still unable to start engine. Computer pointed to burnt sensors somewhere around headlights. Changed both engine still not starting.
does anybody have an idea what the problem is?
How about a detailed description of the noise and when it made the noise and exactly what was done to the car. “Fixed” is not very helpful. 
after the engine was rebuilt the car was running but was making a noise like something was hitting inside the engine tactacatactac was what is sounded like the first time. i don’t konw what he did but the problem went away… now when i came to pick up the car it couldnot start
i am not a mechanic so it is hard to explain…i will contact him so to have more details
thanks again
more details: he said: " he changed the timing belt,the water pump, cylinder head the car was running but was making a sound which seems to be coming from the driver belt. the driver belt was removed and changed the noise stopped. the car was parked. the following day the car didnot start. The computer pointed to the engine speed sensors…both were changed. The car still does not start. i am thinking about taking to the dealership at last for a more complete diagnostic…i dont know how they will charge for that…income is limited.
thanks for helping