Are you looking to update for or just to fix it?
If it's for a fix, I can try to help you narrow down the best version of this firmware. Download MSD6A638 T8E2 Toshiba 43U7750 170207 zip
The firmware for the (using the MSD6A638-T8E2 main board) is a 4K UHD smart TV software package often used to resolve issues like stuck logos, stuck startup, or corrupted system software. Key Features and Details of the Firmware Upgrade: Chassis/Board: MSD6A638-T8E2 Resolution: 4K UHD (3840 x 2160). Type: USB Update/Firmware Flash. Are you looking to update for or just to fix it
What is the with the TV (e.g., won't turn on, stuck on logo)? won't turn on