GSN 1805141731:
the Ogryn becomes Frenzied (see page 144) and gains an additional +10 Strength and +10 Toughness until his Comrade is either safe or dead.
Basic English reading comprehension dictates the Frenzy ends when the Comrade is safe or dead.
FRENZY page 144, Only War Core:
Tier: 1
Prerequisite: None
Aptitudes: Strength, Offence
The character’s temper and passion boil just below the surface of his psyche, mostly held in check by his rational mind, but easily released when needed. If the character spends one full Round fueling his anger—by flagellation, drugs, or other means—on the next Round he goes into an uncontrolled rage, gaining a +10 bonus to Weapon Skill, Strength, Toughness, and Willpower, but suffering a –20 penalty to Ballistic Skill, Intelligence, and Fellowship—note that Characteristic penalties are different from Characteristic Damage (see page 188), and cannot reduce a Characteristic below 1. While Frenzied, the character must attack the nearest enemy in melee combat if possible. If he is not engaged with the nearest enemy, he must move towards that enemy and engage it if possible. The character will not take obviously suicidal actions such as leaping off a building in order to engage someone on the ground, but he will take any actions that have a reasonable opportunity to engage in melee with the nearest enemy.
While Frenzied, he is immune to Fear, Pinning, stunning effects, the effects of Fatigue, and he may not Parry, retreat, or flee. He remains Frenzied for the duration of the combat. Characters may not use psychic powers while Frenzied. After combat ends, or if there are no more eligible enemy targets for the character to attack, he can make a Willpower Test to snap out of his Frenzy. If he fails, he must continue to attack, favouring NPCs over PCs. Each successive Round, however, he may make another Willpower Test, with a cumulative +10 bonus to return to a stable state of mind and come out of Frenzy. After Frenzying, a character may not Frenzy again for at least an hour as he recovers his mental and physical strength.
I am following basic English reading comprehension. Bolding mine but it's pretty explicit as to how a Frenzy ends.
