No, he has waived the right to appeal. He needs to file a motion to withdraw his guilty plea.
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It sounds like you are familiar with this process...if so, would you mind fleshing this out a bit?
To whom would he file the motion?
What would be the next set of steps once filed?
If things don’t pan out, would he be able to eventually get in front of the Supreme Court?
Sorry I had to go to sleep. No, I know only a little, not a real expert. But I think it is as simple as filing a motion before the new judge assigned to the case.