GM328 out of order [solved]

[Dumidan]

There should be a form of autotest procedure inside the ATMega, which causes the initialisation to be VERY long, and made me think about quartz problem...

That is right. If the 3 test terminals are short-circuited at start-up, the self-calibration procedure is started.

[PBh]

I would sooner expect the 328P to be damaged, these testers don't have much for input protection.

For the component socket 3 inputs, GM328 DO have protection diodes TO Vcc and GND and a TVS.