This TV?
https://images0.boattrader.com/resize/1/26/2/6752602_20180620140546578_1_LARGE.jpg?t=1305768
If so, can close-up images please be provided showing the frame, including the corners?
It looks like Sea Ray used a standard fixed-mount wall-mount bracket, then attached a picture frame around the perimeter.
If all that is correct, then I would guess there are hidden screws holding the picture frame together. Sea Ray has used the glued padded vinyl covering that is then loosely tucked over the screws.
Can the covering be pressed upon to feel the hidden screw heads? If discovered, can the vinyl be carefully peeled back to reveal / unscrew the corners on the frame?