Free down load of monitor manuals

Checking online can help, but to be sure of the instructions, or manual from an online source you should look up the exact make and model manual. One such place has instructions on this link.
Detailed Instructions of Polar heart rate monitors

http://h10025.www1.hp.com/ewfrf/wc/manualCategory?cc=us&lc=en&dlc=en&document=&product=3543988 Check the manual

I use thin flat blade screw driver to crack it open at the bottom edge and work you way around.
It is not easy if you have never open the moniotrs before.

http://www.lcdrepair.us/E172fpbvideo.html

See my albums also:
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm/

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.

Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.

That will be the first suspect just like all the failed moniotrs as shown here:
Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague
Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.
Please post back what you find.

Service manual: http://www.eserviceinfo.com/downloadsm/35483/BenQ_Q7T4-FP71G.html

This is almost the same as DELL 17" LCD (Benq makes Dell moniotrs).
Look for shorted out transistors and cold solder joints, fuse in the inverter section.
See failed Dell monitors here.
Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague

Please try instructions I posted here on how to unlock HP monitor:
http://www.fixya.com/support/r4460477-hp_vs_15_17_19_f_1705_1905_lock

You should also down load user manual from HP.
Please post back.
http://s807.photobucket.com/home/budm/allalbums

Check the capacitors (caps with bulging tops) in the power supply, also look for loose LCD panel ribbon cable. See example of failed VIEWSONIC moniotrs here: http://s807.photobucket.com/home/budm/allalbums
http://en.wikipedia.org/wiki/Capacitor_plague
Post back what you find inside.

Try an external monitor, if still nothing, power down, remove battery / /tap start button to de energise system / remove / replace ram stick (s).

If stil no go may me mobo / faulty ram(assuming there is NO posting beep) / faulty CPU.

If ext monitor works then prob with monitor itself.

Get moniotr wiring / ribbon plugs checked.

You may need to load the monitor drivers.

I assume your PC sound is OK.

When you are plugging the green lead in the Moniotr / PC do you hear any noise from the monitor?? if not may be faulty.

Try plugging a friends set of speakers into the back of your PC.

More likely to be bad caps for monitor this old, common problems for ALL brands. See some samples here of bad caps and failed moniotrs: http://s807.photobucket.com/albums/yy352/budm/Bad%20capacitors/