The tech giant Kakao Corporation has yet to fully restore all its services, two days after a fire at a data center caused massive malfunctions and paralyzed the nation heavily dependent on those services.

According to the company, the primary functions of its mobile messaging service, Kakao Talk, were restored about ten hours after the incident, which occurred on Saturday at the Seongnam data center in Pangyo, where the firm's servers are located.

However, some important messaging app services remained dormant till late Sunday, preventing users from accessing them. 

Derivative functions such as sending photos and videos, and creating "open chatrooms" have been gradually returning to normal since late Sunday night, but they are also yet to be fully restored. Other services offered by Kakao’s affiliates, such as electric bike-sharing and Kakao map services, are still experiencing issues.  

The protracted recovery is attributed to step-by-step safety check procedures that are being undertaken at the Pangyo data center.  

Preliminary police investigation indicates that the fire began with one of the 30 power supply devices on the third basement floor of the building. The police and related agencies, such as the National Forensic Service, plan to conduct a joint investigation on Monday to find a more precise cause.