DIAGNOSIS The monitor's power LED is in its startup diagnostic mode. The main board isn't completing its boot sequence. A corrupted firmware is the most common cause.
FIX First, disconnect the monitor from power and all signal cables. Press and hold the monitor's power button for 30 seconds. Reconnect only the power cable. Turn it on. If the LED still cycles, you need a firmware recovery. Download the official firmware file from Samsung's support site for the LS57CG952NNXZA model onto a USB drive formatted as FAT32. With the monitor off, plug the USB into the service port on the back. Turn the monitor on. The LED will flash during the update. Do not disconnect power.
IF THAT DIDN'T WORK The main board may have failed. This requires a professional repair or board replacement. Contact Samsung support with your serial number.
HEADS UP Never interrupt a firmware update. A power loss during this process can brick the monitor permanently.