The Australian Navy's largest warship had a major electrical failure shortly after completing its humanitarian mission to Tonga, following the January 14 volcanic eruption and tsunami.
Despite days of emergency work, the HMAS Adelaide was still experiencing issues, Australian news outlet ABC reported.
An email showed the HMAS Adelaide's commander had said: "Marine Technical Department have worked throughout the past few days to restore power and get us operational again."
According to ABC, Capt Stuart Watters said: "We are still experiencing issues with external communications and wanted to let you know that everyone on board is safe.
"We want to thank the technical team for their hard work in hot and difficult conditions which is enabling us to complete our task and restore services and communications."
Several members of the crew said most of the ship's company were now sleeping above deck because of the power problems.
HMAS Adelaide docked in Tonga last week to deliver aid despite a Covid-19 outbreak that occurred on board shortly after it had departed Australia. About 24 sailors on board the vessel were reported infected on Tuesday.
The Australian government said its ship had completed the 3,300-kilometer voyage from Brisbane and would deliver supplies without contact with the local population to avoid infections.
Capt Watters told local news outlets that the crew members originally infected with the virus have now returned to duty.
Under pandemic measures, Tonga typically requires visitors to quarantine for three weeks on arrival and that complicates the international disaster response. All international aid is to be delivered without local contact.
Since the pandemic began, Tonga has reported just a single case of Covid-19. It is one of the few countries in the world currently completely virus free. About 61 per cent of Tongans are fully vaccinated, according to Our World in Data.
