Had a nightmare with the car over the last two weeks

I had a new clutch fitted and the chap who did it never fit the earth wire back up properly so after much investigating found out the ECU had been blown, replaced this and the car would still not start with the key but when you run a wire from the battery to the connector in front of the starter motor it starts a treat.
I was adviced that this bypasses the ignition switch but after replacing the swich I am still getting nothing from the key.
I am wondering if I may also need to replace the small unit on top of the ECU ?
Cheers