When sound is normal but the screen remains dark, LED backlight failure is a common possibility. A faint flashlight image supports that theory but is not a complete diagnosis; driver output and strip current must be measured.
A lit but white, partial or striped screen points toward T-CON, ribbon or panel-signal checks. Cracks and liquid marks suggest physical panel damage.
High-voltage parts make home disassembly unsafe. A TV technician should use measurements to separate backlight, board and panel faults.