If there is a flashing led on front of the monitor, 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.
The 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
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.
faults that can occurr suddenly are a blown capacitor on power board,
the inverter board powering up backlight lamp has blown, or a fault on
main lcd controller board.
check also the video cable, if the cable
is shorting, or the connector is bad, you can get same flashing state
because of the video cable.
Check connectors, try moving the video cable, and if the cable is not built in, then also try a replacement cable.
If under warranty contact Viewsonic to find out a Viewsonic service point.
See:ViewSonic - Support & Service
If you want to repair at your own expenses, just locate any good qualified repairer.