The monitor is probably on protection.
To start unplug monitor
from power and from computer and test computer with different monitor
to find out if it is monitor or computer fault.
If it is computer fault and no video signal , then test:
- Video cable.
- Video adapter on PC (sometimes integrated on motherboard)
- Motherboard.
If it is monitor fault , then the monitor is on protection.
When on protection you keep having a flashing
led on front of the monitor , and monitor turning off by itself after a while,
that indicates a fault condition.
The flashing light indicates a diagnostic state called protection.
When the Monitor goes on protection there are only two possible causes.
1The
internal circuits are jammed because of electrostatic
charges accumulating on capacitors, or because of a wrong voltage read
by the main chip on your monitor controller board. this started the
protection circuit.
2 The protection circuit detected a wrong
voltage or a broken contact, identified an internal fault and kicked in
, starting the flashing light.
If
you are in situation one, then the monitor will reset just unplugging
power cord for one or two hours,sometimes even minutes.
If you are in situation 2 , then there is an internal fault.
Common
faults
that can occurr are a blown capacitor on power board, faulty inverter
board, faulty input board, or a fault on LCD Digital Controller board.
Check also
the video cable or any external connection cable, if the cable is shorting, or the connector is bad, you
can get same flashing state because of the video cable.
Try moving the video cable, and if the cable is not built in, then also try a replacement cable.
If under warranty contact the manufacturer ringing the number on the user manual
If you want to repair at your own expenses, just locate any good qualified repairer.
If the display responses or from dim to lighter 100% you have a problem to ABL find this at the bottom of horinzontal section near at flyback transformer pins trace the line of ABL for dried solder, open resistor if nothing happen find the Video IC at chroma section and replace it. follow this... 
For LG & Redfox you found LM1269NA Visit this site for seaching semiconductor matches www.alldatasheet.com Good luck.
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