We have investigated ourselves and found nothing wrong.
Unless SuperMicro hires an independent, third-party auditor, the ball is still in their court.
"Computer hardware maker Super Micro Computer Inc told customers on Tuesday that an outside investigations firm had found no evidence of any malicious hardware in its current or older-model motherboards."
Further down
"A person familiar with the analysis told Reuters it had been conducted by global firm Nardello & Co and that customers could ask for more detail on that company’s findings."