Emitt Rhodes, who was a rising pop star in the early 1970s, with songwriting and singing skills likened to those of Paul McCartney, then gave up performing for more than 40 years, becoming a cult figure among musicians, died July 19 at his home in Hawthorne, Calif. He was 70.

The death was confirmed by Chris Price, a musician who produced Mr. Rhodes’s 2016 comeback album, “Rainbow Ends.” He did not know the specific cause.

Mr. Rhodes was something of a prodigy of pop music, playing in bands by 14 and signing his first major-label contract at 16, when he was with the group Merry-Go-Round.

By 19, he had become a solo performer, writing all of his songs, playing all the instruments and producing the recordings in a shed in his backyard — practically creating the idea of the home studio.

His self-titled debut album from 1970, which showed Mr. Rhodes on the cover moodily peering through a scorched windowpane, led a critic for Billboard to call him “one of the finest artists on the music scene today.” The album reached No. 29 on the Billboard charts, and one of its singles, “Fresh as a Daisy,” topped out at No. 54.

The music was bright, catchy and meticulously arranged, and Mr. Rhodes’s soaring tenor voice invited immediate comparisons with McCartney. Rumors began to circulate that “Emitt Rhodes” was a pseudonym for McCartney or that the Beatles had recorded an unreleased album that was appearing under a made-up name; others speculated that the recently broken-up Beatles were working incognito as Mr. Rhodes’s backup band.

When it became apparent that Mr. Rhodes was playing the parts of John, Paul, George and Ringo — and their producer, George Martin — all by himself, he was dubbed the “one-man Beatles.”

“It was really flattering,” the very real Mr. Rhodes told The Washington Post in 2002. “Those guys were my idols.”

A second album, “Mirror,” appeared in 1971, and Mr. Rhodes — slender, clean-shaven and darkly handsome in those days — toured the country, seemingly on his way to stardom.

“I was chased, I had underwear thrown at me, I had groupies,” he told The Post. “It was like being in ‘A Hard Day’s Night.’ ”

In 1973, Mr. Rhodes released the aptly titled “Farewell to Paradise,” his somewhat disillusioned goodbye to the life of a budding rock star. He was 23.

When he had agreed to his record deal with the Dunhill label four years earlier, Mr. Rhodes was required to produce a new album every six months for three years. Moreover, he had signed away the royalty rights to his songs “in perpetuity.”

Busy writing the songs, singing, playing all the instruments and producing polished little power-pop gems, Mr. Rhodes fell behind the schedule dictated by his contract. His record company withheld his royalties and sued him for $250,000 — “more money than I’d ever seen,” Mr. Rhodes later said. “I was horribly confused.”

He fell silent. He stopped writing music and went through personal problems, which he said included depression, drinking, drugs and divorce. The backyard studio went unused.

Mr. Rhodes spent the next 30 years working as a staff engineer and producer with Elektra and other recording studios. Nonetheless, his music endured, even as his mystery grew.

“He was a deep, deep cult figure,” said filmmaker Tony Blass, who interviewed Mr. Rhodes for a 2009 Italian-produced documentary, “The One Man Beatles.”

In the 1980s, the all-female band the Bangles recorded Mr. Rhodes’s “Live,” which he had written and performed on television at 17. Other musicians hailed him as a lost musical hero, a misunderstood pop genius not unlike Brian Wilson, the troubled leader of the Beach Boys — who had grown up blocks away from Mr. Rhodes in Hawthorne, a working-class Los Angeles suburb.

A more apt comparison might be with songwriter Tandyn Almer, who wrote the 1966 hit “Along Comes Mary” for the Association and contributed to some Beach Boys songs before living his final years in obscurity in a basement apartment in Northern Virginia.

In 2001, director Wes Anderson — on a suggestion from actor Jason Schwartzman — used one of Mr. Rhodes’s songs, the wistful “Lullabye,” in the movie “The Royal Tenenbaums.” When Mr. Rhodes saw the movie with his 10-year-old daughter, he heard the words he had written in 1970:

Tears that angels cry

And they darken all the sky

When the one you love says goodbye

“I’d forgotten the tune,” he told The Post, but added, “My little girl was proud of me.”

Because of the contract he signed as a teenager, Mr. Rhodes did not see any royalties from “Lullabye” or any of his other songs. Eventually, new agreements were worked out, allowing him to profit from his earlier work.

The 2009 documentary about Mr. Rhodes received several awards in Europe and helped raise his profile. He also became friends with musician Chris Price, who knocked on Mr. Rhodes’s door in 2007 and began to meet him for lunch.

Mr. Rhodes gave Price, now with the group Bebopalula, musical pointers but refused to discuss his earlier life. There had been occasions in the 1980s and 1990s when record labels tried to bring Mr. Rhodes back to the studio, but the plans always fell through.

Eventually, he warmed up to Price and showed him Manila folders containing more than 20 new songs. Many of them, such as “What’s a Man to Do,” were marked by a mature, wounded lyricism:

I hear the whispers

I hear the talk

I count the minutes

I watch the clock

I fear she’s leaving

Won’t change her mind

The door is closing

I’m out of time

Price convinced Mr. Rhodes that it was time to sing again. The old studio, which had shag carpet from the 1970s and was being used as a storage shed, was cleaned out and put back in service.

Musicians who had long revered Mr. Rhodes were brought in, including guitarist Jason Falkner, keyboardist Roger Joseph Manning Jr. and drummer Joe Seiders, with special appearances by singers Aimee Mann and Susanna Hoffs. Mr. Rhodes was back in his element, his voice as expressive as it had been in his youth.

Mr. Rhodes’s first album in 43 years, “Rainbow Ends,” appeared to glowing reviews in 2016.

“He wouldn’t put his name on just anything,” Price said in an interview. “We went through every song, every chord, every bar.”

Emitt Lynn Rhodes was born Feb. 25, 1950, in Decatur, Ill., and moved with his family to Hawthorne at age 4. His father was a machinist, his mother a homemaker.

Mr. Rhodes was interested in music from an early age and began his career as a drummer in a band with friends from his high school. By 16, he was the lead guitarist and singer for Merry-Go-Round, penning the minor hit “You’re a Very Lovely Woman,” along with “Live.”

“I wouldn’t call him a perfectionist,” Price said of Mr. Rhodes’s songwriting style. “I would say he had very keen instincts and seemed to know what would make a listener respond to a song emotionally.”

Perhaps a more lasting influence, however, was Mr. Rhodes’s single-minded dedication to his craft, exemplified by his professional-quality home studio.

“He was a home-recording guy before anybody else was doing it,” Price said. “He made it so that you couldn’t distinguish something he made from something made at Capitol Records. He did something out of necessity to him that later became commonplace.

“This has fundamentally changed the way music is made.”

Mr. Rhodes’s marriages to Kathy Sharp and Charnelle Smith ended in divorce. Survivors include his fiancee, Valerie Eaton of Toronto; two sons from his first marriage; and a daughter from his second marriage.

After releasing his 2016 album, Mr. Rhodes seemed to have decided he had nothing more to say. He canceled a comeback appearance scheduled at the South by Southwest festival in Austin, choosing to stay at home in Hawthorne, in the same house he had lived in for decades. In the title track of “Rainbow Ends,” he sang:

I wanna be somewhere far away

Somewhere where I won’t be afraid

I wanna be sheltered safe and warm

I wanna be somewhere far from harm.