TV dark, vertical, shaded bands

I have 2 shaded vertical bands (about 6” wide) on my Hisense 50H5G LED LCD TV. The bands have sharp edges, a shaded display, and are directly above the panel’s bonded ribbon cables (#1 and #3) (total of 6 areas; #1-3 for left, #4-6 for right of screen). It is on all inputs and at the splash screen. It is not LED strips out - all are lit. They are not staticky lines.

I have replaced the T-Con board, and there was no difference. I've swapped ribbon cables leaving T-con (left and right) to the buffer boards with no changes. I've reseated the LVDS cable at T-con input and at main board output - no change. I've inspected and pressed on bonded ribbon cables at the panel and on the buffer board with no effect.

Disconnecting the ribbon cable from T-con board to buffer board (#1-3 ribbons), the screen is white and perfectly continuous (no shaded bands). In service mode, the shaded bands appear for R, G, B and white color screens. (I now guess this is only because it is the backlight showing through).

(There is a similar dim anomaly at band area #4 (right side buffer board) at boot-up splash screen, but it goes away after the splash screen and the normal screen is up. Actually after viewing my photos, each band gets progressively better i.e. #1 bad, #3 slightly better, #4 trace amount.)

Thanks

Note: the other aberrations are from taking the picture.