The blaze broke out in Ruyi Inn in Dukezong Ancient Town after its owner Tang Ying forgot to turn off the heater, causing it to set fire to a curtain, read a statement from the fire-fighting and disaster-relief headquarters.
Tang is being investigated for negligently causing the fire, state-run Xinhua news agency reported.
A report earlier this week stated that a "careless use of electricity" by Tang led to the electrical fault.
Shangri-la resort, famous for its ancient wooden structures and cultural relics, was destroyed in the fire on January 11, and also forced the evacuation of 2,600 people.
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While more than 240 houses were damaged, another 43 had to be dismantled. The blaze lasted about ten hours.
Apart from the houses, shops and infrastructure facilities, the fire damaged cultural relics, Tibetan thangka and other Tibetan art.
Dukezong is one of the most renowned resorts in Shangri-la, known for its well-preserved ancient Tibetan dwellings.