He crossed the line when he destroyed his phone.
Again, possibly his footballs were a bit deflated as a matter of preference. Others have done the same, others prefer them over-inflated... In the second half of the Colts game with the balls supposedly at regulation pressure, he did even better. Like I said, a minor issue.
He destroyed his phone, possibly for unrelated reasons (maybe he had a text message there inviting Gronk to come over for a threesome with Gisele, LOL), but even if it was related, it was in response to Goodell's unreasonable persecution. He was probably guilty of deflating the balls a little which in my opinion is not a big deal and doesn't qualify as hardcore cheating, and didn't want to give Goodell the satisfaction of ultimate proof, if there was something in his phone. It's all very doubtful because the NFL did have the text messages from the recipients, so, no real point in destroying his own phone (which he had done before, for unrelated reasons).
Recently I dismantled and destroyed five hard disks of old laptops before sending them to the landfill, due to the risk of identity theft, and I'm not a celebrity. For someone like Brady, having an old phone around is potentially much more of a problem. So, like he said, when he upgrades phones he destroys the old one. That's one explanation.
Like I said, if this explanation is phony (pun intended) and there was something related to Deflategate in the phone (as opposed to stuff about his wife, for example, as simple as sexting to her), it's still no big deal, because Deflategate itself was no big deal, as far as real cheating goes.
Who cares if some quarterbacks manipulate a little the ball pressure to fit their preferences, up or down? Others have done it.
If Goodell didn't want to appear tough (due to the issue of Robert Kraft, and due to previous complacency with domestic violence, he was on the hot seat), Deflategate would never have happened. It would have ended in a minor equipment fine, case closed.
Deflategate and its ridiculous expenses (even involving tax-payer money that funds the court system) was exclusive the idiotic Goodell's doing.
As a non-Patriots fan I don't like that Brady wins so much... But I dislike Goodell much more.