Hi.
When the unit is in power save mode, the led is amber and the led amber light is solid.
If the led is of a different color, or if the led light is flashing, then the unit is not in Power Save mode, but it is probably defective.
If the TV is in power save mode (amber led and solid):
Use buttons on the side of TV either one of the channel buttons, or on-off button, or input button should wake up the TV unless faulty. Once TV is on, use input button to switch from TV to monitor. (see manual at page 6)
If TV is used as monitor and does not wake up when you use computer mouse or keyboard, check connection cable from computer to monitor.
If LED is not amber, or if LED is flashing, then the TV is faulty. In that case contact Dell at one of the numbers listed on the owners manual to arrange repair.
Here the manual.Regards.
Ginko.