Can you post pictures of what you can see with the bits that you've removed taken out?
Can you see the inaccessible bolts on the metal sub-frame? If you don't care about the frame in particular, can you possibly cut it with a cut-off wheel (in a Dremel or little angle grinder) or something? Do you believe that's what the television is mounted to?
Is there anything interesting to see from the insides of the adjacent side cabinets? Maybe the "walls" separating the cabinets are removable somehow.
It would seem that there must be some sort of access at least to the back of the television for power and cable/antenna hookup, but sometimes what I think must be accessible and what the makers determine needs access are not entirely in agreement.