I had a Mitsubishi receiver once with "random pops". Eventually it got so bad that it then started producing 60Hz hums. Turned out it was a cracked circuit board around the transformer.

It is quite possible that they did not solve all the issues with that unit and that if there were any hairline cracks in the circuit board (very difficult to trace) shipping further opened up the cracks so that you are now experiencing what they did not troubleshoot. This is of course just a guess.