TBH probably unlikely. While it's not impossible they fail, it's pretty uncommon. It also likely won't work because anti-theft will be a problem when you swap the ECU, either because the BCM from the donor is also in the car, or because your current ECU has VATS has been disabled. If your mechanic is saying the wiring is dodgy you should start there by seeing if it's rubbed through anywhere on the loom or there are places where it's shorting.
It's using the Commodore auto yeah?
Are you sure it's a VY ECU? Usually people go down the path of using a VS one when they do an Ecotec conversion, plus if it's a legit VY L67 ECU it'll have a memcal. Post up the details about what's on the sticker on the ECU, won't make a difference but may make it easier to trouble shoot.