Cell doors swung open yesterday to free 277 inmates after a U.S. Supreme Court justice lifted his ban on a court-ordered mass release designed to relieve overcrowding in the state penal system.

A cheer went up in state prisons as word spread that Justice Lewis F. Powell Jr. had removed the temporary stay he issued late Thursday, six hours before the relases were originally scheduled to begin.

Inmates carrying their belongings in brown paper bags began leaving the prisons shortly after noon. With $10 from the state and a bus ticket home, if they desired, many were ferried in prison vans to bus stations.

Meanwhile, state Attorney General Charles Graddick made a last-ditch attempt to keep at least some of the in;mates from getting out.

He sought a second temporary stay from Chief Justice Warren E. Burger and filed a motion with the U.S. District Court in Montgomery saying the court's original order mandating the prisoner release was no longer valid because it was dated for Friday, not yesterday.

Yesterday evening Graddick said he had not heard anything from either court and that the issue was virtually dead. "The fact that they turned them loose immediately just about mooted our chances of any further relief," he said.