Hi. Please need some assistance. I have a canon 750d that does not switch on when i insert the sd card inside the camera. Once i eject the sd card and switch on the camera it switches on and i can do functions as usual but once i put in an sd card no powering up. Is the sd card slot damaged? Thanks in advance.
The 750D/T6i Firmware fully supports SDXC (2TB limit) and is not restricted to SDHC (32 GB) only.
Since the OP states that two cards work on another 750D, they must be properly formatted to FAT32 and not NTFS. Even an improperly formatted card should not cause the camera to not turn on - it might trigger a "card must be formatted" warning, but should not prevent the camera from powering up.
However, strange system faults can occur, and it certainly can't hurt to find a 8GB or 16GB SDHC card (if you still can) to try to absolutely eliminate the "card size" issue.