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On the night they celebrated the 60th anniversary of the Beatles’ invasion of Shea Stadium, the crashing Mets endured yet another hard day’s night at Citi Field.

HELP!

Deadline acquisition Ryan Helsley and the bullpen coughed up a late lead for the second consecutive night as the Mets fell for the 14th time in 16 games with an 11-9 shootout loss to the Mariners in Flushing.

Carlos Mendoza’s flailing team only maintained a half-game lead for the final NL wild-card spot because the Reds flushed an 8-1 advantage and lost to the scorching Brewers in Cincinnati.

Sean Manaea was tagged for two homers and four runs on six hits in five innings, his seventh straight start since returning from the injured list without completing at least six. The lefty now sports a 7.98 ERA over his past three outings.

Helsley couldn’t hold a 6-5 cushion in the seventh — after also squandering an eighth-inning lead in Thursday’s loss to the Braves — permitting Seattle to tie the score on doubles by MLB home-run leader Cal Raleigh and Eugenio Suarez.

The Mariners then added four more runs in the inning on run-scoring hits by Dominic Canzone and Donovan Solano and a two-run double by Cole Young against lefty Brooks Raley, with both relievers booed off the mound.

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Demoted starter Frankie Montas also heard jeers while giving up an additional run in the eighth, before Francisco Alvarez pulled the Mets back within two with a three-run homer to right in the bottom half.

Francisco Lindor also went deep twice and Juan Soto ripped his 30th of the year earlier in the game for the Mets, whose record since June 12 is now an abysmal 19-34.

Beforehand, the Mets (64-58 overall) staged a pregame concert by a tribute band to honor the anniversary of the Fab Four’s 1965 concert at Shea, and they used photoshopped pictures of their current players dressed in 1960s-era Beatles garb and haircuts on the scoreboard throughout the game.

The Mariners reached Manaea for a run in the first inning on a leadoff single by Randy Arozarena and an RBI double into the left-field corner by Julio Rodriguez.

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Lindor answered right away with his second home run in as many nights and 23rd of the season, an opposite-field shot to left against Seattle starter Luis Castillo. It marked Lindor’s seventh leadoff home run of the year, tying the franchise record set by Curtis Granderson in both 2015 and 2016.

Mitch Garver put Manaea in another hole in the second, clocking a 3-2 sweeper over the wall in center for his seventh homer and a 2-1 Seattle lead.

But Alvarez evened the score again in the bottom half with a two-out RBI single to center after Jeff McNeil had opened the inning against Castillo with a double to right.

Lindor nudged the Mets ahead 3-2 with a run-scoring single to center, but Raleigh pulled an 0-1 four-seamer from Manaea over the left-field wall for his MLB-leading 46th of the season and a 4-3 Seattle lead in the third

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That moved Raleigh within two of Salvador Perez’s single-season record of 48 home runs by a player whose primary position is catcher in 2021.

Lindor responded again in the bottom of the inning with his 24th, a two-run shot to right off Castillo for his third multi-homer game of the year. Soto followed with his 30th of the year on Castillo’s next pitch for a 6-4 Mets advantage.

The Mariners halved that deficit on Young’s RBI single to center off reliever Tyler Rogers in the sixth.