Antonio Brown is trying for the Helmetgate Hail Mary.

The Raiders wide receiver is continuing his bizarre fight over which helmet he uses, despite the NFL and NFLPA shutting down his pleas.

Brown wants to wear the Schutt Air Advantage that he has always used, but the league has deemed it unsafe. There are two more helmets that Brown is getting tested — versions of the same model made in 2014 and 2010 — but it is likely to still be a losing battle, according to NFL Network. The last-ditch effort is “moot” in the minds of testers, the network reported Monday, because the helmet was tested and failed, regardless of which year it was made in.

The news comes a day after Raiders general manager Mike Mayock issued an ultimatum to Brown to “be all in or all out.”

“We’ve worked very closely with the Raiders, and we will continue to work very closely with the Raiders,” Brown’s agent Drew Rosenhaus said Sunday night on WSVN-TV in South Florida. “I’m not sure that we agree that we’ve exhausted all the options, as Mike Mayock said. But there’s no doubt it’s still an ongoing process. We are trying to work with the team and the league and the union to come up with a solution. We haven’t figured it out yet. To say that AB is upset about the decision to not let him wear his helmet is accurate, but we’re still processing it and figuring it out. I wouldn’t make too much about him not being there today, as much as we’re still trying to come up with a solution that works for everyone.”

The helmet saga, not his frostbitten feet, kept Brown away from the team Sunday, but he returned to the Raiders facility Monday, according to ESPN.

Mayock did little to hide his frustration over Brown on Sunday.

“You all know that AB is not here today. So here’s the bottom line: He’s upset about the helmet issue. We have supported that. We appreciate that,” Mayock told reporters. “But at this point, we’ve pretty much exhausted all avenues of relief. So from our perspective, it’s time for him to be all in or all out. So we’re hoping he’s back soon. We’ve got 89 guys busting their tails. We are really excited about where this franchise is going and we hope AB is going to be a big part of it starting Week 1 against Denver. End of story. No questions.”

Brown filed a grievance and lost on Aug. 12. Then he tried to find newer versions of his preferred Schutt helmet model that were less than 10 years old — even asking Twitter for help — but apparently the league is intent on closing that loophole. ESPN reported he told the Raiders he would not play football again if he could not wear his helmet of choice, though he has since denied that story.