LCD goes blank after a few seconds

I have a Samsung SyncMaster 912n 19in LCD. After 8 years it goes blank after ~30 seconds after power on.

Power off/on maybe 10 seconds then again 5 seconds... I am aware of the capacitor problem. I opened the LCD up and found two caps that had slight bulging on the power supply board. I ordered a cap repair kit for the specific power supply board so I would have the proper ratings. I also checked all connectors and reseated them.

Replaced the caps and fired up the LCD. No help - same problem. Replaced the whole power supply board with a known working board - same problem. Replaced the logic/T-con board with a working board - same problem.

So now I am down about $36 - about the same for a used similar LCD monitor. Any more thoughts? This happens even if the monitor is not connected to a PC so it is not cables/virus/monitor settings. Seems a shame to toss a clean new looking LCD monitor in the trash........

????