A door on a Biman flight was left unlocked before take-off. What happened?

A Biman Bangladesh Airlines flight was en route from Dhaka to Qatar's Doha via Chattogram on Wednesday afternoon when it suddenly slowed down on the runway and returned to the hangar.
After the incident on Wednesday afternoon, authorities announced that the indication panels on the Boeing 737-8 model craft showed two doors on the aircraft's central compartment were 'unlocked'.
The flight - BG-125 - was delayed as the aircraft's engineers fixed the glass of the rear emergency exit door.
Mohammad Hatim, the executive president of BKMEA and a passenger on the flight, took to Facebook to express his frustration over the incident.

In his post, the aeroplane's engineers were seen fixing the glass of the exit door while the passengers impatiently waited inside the aircraft, panting in the heat as the air conditioning was turned off.
Although he thanked the pilot for fixing the issue before take-off, Hatim said: "I have travelled on board Biman Bangladesh Airlines several times before with the prime minister. I have also gone for Hajj. But today, travelling as a regular passenger, I had a bad experience. I have heard of such bad experiences in Biman Bangladesh from other passengers. But today, I, myself, am a victim."
However, the Biman Bangladesh Airlines  authorities say that the incident was not a serious one.
Boshra Islam, Biman's public relations officer, told bdnews24.com: "The problem wasn't serious. The pilot was alerted when the indicator panel showed that the doors were unlocked before take-off. The engineers resolved the issue when he returned to the hangar. The flight then took off at 5:47pm after the minor error was fixed."