Since the area had been flooded, I would not expect the electrician to have done his due diligence and replaced every connection point that could have been compromised.

Low voltage (brown out) is a common symptom to locked up processors. So take your DMM and measure the voltage on the AC plug the TV is plugged into. Then do my little trick of plugging your Shop Vac into the outlet and measure the voltage again when it is on (load test).
If your voltage drops below 108VAC, you have a problem somewhere in the electrical. Also if you start out at a voltage like 125VAC and under load it drops to 110VAC - then you still have a major issue. 15 volt drop is excessive.

Another thought, since there is a lift involved as Rob mentioned. Measure the voltage & current when that is operating. A lift motor that is binding could draw an excessive amount of current, causing a big voltage drop affecting the TV.