My e152fb dell monitor was not working..

Your monitor should turn on without a source and display the floating 'Dell - self-test Feature Check' message. If it does not, verify the power LED is on "GREEN" and indicating either power on / diagnostics mode or "Amber" power saving mode. If neither indication you have power problems. If these symptoms do not apply, shine a light on the sceen and see if there is a faint image. If this is true, you have backlight problems.

As you had stated that the monitor is working if the power brick is off.The back light shutdown might be a cause of static from your power brick, or other thing is it might be your setting for back light level or power scheme.Some configuration needs to open BIOS settings.To check if the power brick is the cause of problem is good to have a known good one or try to monitor if it is charging or not by monitoring the battery indicator if the power brick is off.

no display showing on moniter

This sounds like the power inverter is failed.. It's what pumps up the power for the light in the monitor.
You could try unplug the sound bar from the back of monitor if you have the sound bar installed. Just a maybe..
To fix the inverter (replace) is usually better to buy newmonitor unless you do it your self.
The defective LCD Backlight inverter will cause the following symptoms:

• No Display, but Power Indicate light stay on green (Or Blue).
• Screen flash on and off and the power indicate light stays on green (or Blue).
• Dim Display

Go here to start looking if you want to try yourself. http://www.lcdparts.net/DI3D.aspx

Disconnect the display from the Computer and remove its power plug. While the display is turned off, press and hold the power button for 30 seconds. After two minutes connect the power cord and the display cord to the Computer and the power source and turn it ON.

If the power indicator on the display keeps blinking, then it's required to open it up to repair it.

test an external monitor and see if the same thing happens. If the display goes out even before your computer gets to the part of loading Windows, it may mean your computer is not booting up, or there is a problem with the LCD. Check and confirm that your system power indicators are okay. If you know your system is turned on, but not display, run the diagnostics from dell using the FN + power button combination. observe if the display will work properly during the test and if you get any error that can indicate the point of failure.

Is the power blinking amber? This is a DPMS power-save mode. With the computer disconnected and the monitor on, do you see the colored self-test block floating around? With the monitor on, computer connected, and you still have no image displayed, take a bright flashlight and examine the screen closely. If you can see a very dim display in the screen, the fluorescent tubes which light up the *background* and provide the vivid picture(sort of like a how an x-ray picture viewer works) are defective. The power light blinking may be the power supply sensing the non-functioning tubes or it could just be bad. If your display is under warranty, replace it. If not, trying to have the monitor repaired for this type of problem is almost as costly as a new one--and there won't be an active warranty on anything else that might fail. Hope I helped you.---Rick

bad capacitors inside the monitor they need to be replaced, or if the power light is blinking then there are transistors that need replacement

try swapping the computer power cable and don't connect the vga cable with the system. if you get a power on self test displayed it makes sure that the monitor is fine. if nothing is displayed you can take it for repairs or else call 1-800-624-9896 its Dell technical support number or log on to support.dell.com