Black screen after bios logo

Hi I have a notebook, hp compaq presario cq50, he works very nice, I can see the logo and even can enter in bios.
The problem is: after bios logo, the screen remain black. not boot. I have try the following stepes:
use a boot cd
use a usb boot
remove batery and use only with the charger.
remove the 2nd batery also reseted bios
remove hdd
remove ram/replace ram
connect to another monitor
load bios to default
… Please help me
ps. the temperature I cant see in bios but my opinion is 30-50 degrees Celsius (is not hot at all)
Answer #1
I can see the logo
can you hit tab and see the post screen of text or set “diagnostic” boot screen in the BIOS
with the HDD in does the HDD activity light flicker during “black screen”
Answer #2
yes, I can hit tab to see status text, also the led is working from hdd, I have also a test in bios to check hdd and ram, they are 100% ok.
Answer #3
also the led is working from hdd
after the boot screen ?
the PC making boot-up sounds ?
I can hit tab to see status text
and it looks right ?
sees ram, CPU & drives correctly ?
Answer #4
[/quote]after the boot screen ?
the PC making boot-up sounds ?

Yes, the beep is ok.and it looks right ?
sees ram, CPU & drives correctly ?

Yes I can see ram, hdd, dvd, etc, is working good until going to "boot" then black screen.
Answer #5
black screen as in not even a blinking cursor at the top left ?
use a boot cd
use a usb boot
do you have or have you tried a DOS based (text) boot disk like Hiren’s BootCD
with the HDD removed will it boot from a CD/DVD
removing everything except HDD, memory & ram should at least give you a “no bootable OS” type error