The mutinous officers here in Cabanas province and El Salvador's embattled minister of defense carefully opened doors today to a face-saving end of the internal revolt that has bitterly shaken this country's U.S.-advised Army.

Lt. Col. Sigifredo Ochoa, who declared his 1,200-man garrison in rebellion Friday and demanded the resignation of Defense Minister Jose Guillermo Garcia, said today his position on Garcia had not changed but added that he would be willing to talk with the defense minister face-to-face in the capital if a secure location could be agreed upon.

"I am telling you that I am not leaving command of Cabanas unless he Garcia goes," Ochoa said this morning as he led reporters on a hike through the mountainous countryside to a mortar demonstration on this little hilltop. "I cannot surrender, because I would betray my officers, my troops and most important, the people of Cabanas."

Ochoa's second in command, Maj. Luis Roberto Rodriguez Sosa, said that "if Garcia stays we are in danger," but that a solution might be possible that would not require Garcia to leave his post at exactly the same time as Ochoa.

It is widely expected that the crisis could result in the resignations of both officers. One government source noted that Garcia will have completed 30 years in the armed forces--normally time for retirement--within the next few months.

In San Salvador, civilian President Alvaro Magana, who has close ties with the military high command, issued a carefully worded statement tonight that skirted clear support of the defense minister and called for "a minutely detailed study of the anomalous institutional situation" caused by the mutiny.

Without mentioning Ochoa by name, the statement ordered compliance with the general order that provoked the crisis last week by assigning Ochoa, one of the Army's most successful battlefield commanders, to the Salvadoran Embassy in Uruguay.

At a press conference earlier in the day, Garcia did not answer the question of whether he would step down with a flat "no." He said instead that "the only one who can ask me to resign is the president, who is also the commander in chief of the armed forces."

Garcia also tacitly conceded what Ochoa has claimed since yesterday morning: that the commander of the Air Force and the head of the powerful 1st Brigade located in the capital's San Carlos garrison were quietly supporting the rebellion.

Neither of these colonels nor their representatives signed an armed forces communique published in today's newspapers that condemned the insubordination in Cabanas.

That document, too, left open a path toward resolving the confrontation. It called for "naming a commission to find a solution in accordance with the highest interests of the armed institution and the Salvadoran people."

The crisis, as both Garcia and Ochoa pointed out, comes at an especially difficult moment for the Salvadoran Army.

Before the end of the month, the Reagan administration must certify to Congress that the Salvadoran government is making progress in improving human rights, investigating the murder of U.S. nuns and agrarian reform advisers, asserting control over the armed forces and implementing political and economic reforms. The actions of the armed forces are crucial in all of these areas.

The impending certification has drawn to El Salvador dozens of observers, including advance men for concerned congressional delegations, special committees of U.S. lawyers, doctors and academics and journalists from the major media. The U.S. observers have encountered a high command apparently impotent in the face of the Army's deep divisions.

At the same time, troops on both sides of the confrontation anticipate some kind of major guerrilla action this week to commemorate the second anniversary of the insurgents' 1981 attempt at a "final offensive."

Today, Ochoa arranged for the three American networks and a camera crew from the Public Broadcasting Service to accompany him on a "patrol" here in the mountains about 20 minutes south of his headquarters in Sensuntepeque, the provincal capital.

The climax came when Ochoa's soldiers set up a 120mm mortar here and lobbed a few rounds across the provincial border into supposed "guerrilla camps" located in the administrative department of San Vicente.

The commander of San Vicente--it was supposed to be clear--had failed at eliminating his guerrilla problem. He is a close friend and ally of Garcia.