If you used a conductive material like Aluminum to shield the PCB, remove it. Temporarily shield it with non-conductive tape, for example, lightly apply scotch tape to it, to prevent a shortcircuit.

Re-place the front of the bezel, the connector and logic board assembly, and keep them stuck to the monitor using tape. Re-connect all internal cables, then connect a working display output and a power cable.

Turn on the monitor, propping it against something solid, or having someone hold it in position. Run tests, for example a full-screen video or a full-screen "stuck pixel fixer"

If the problem reappears, re-apply insulation to the top PCB and repeat step 3.

If the problem does not reappear, remove the tape, re-apply the thick plastic shield using scotch or kapton tape in place of the black tape, and re-assemble the bezel.