Didn't understand this. Why can't you contact Airtel for help? Yes they will charge you for repair or replacement of the drive or even the entire STB but there's no getting around the fact that you will need their support.
Bro that's what I am saying..the bootloader and its signature will be unique to the manufacturer of the STB. The drive itself may be formatted with standard file systems like NTFS/FAT32 or ExtFAT. But without the bootloader and signature the drive will not be recognized by the firmware. All STBs are proprietary systems it is not plug and play like replacing a drive in a USB enclosure.