HP Pavilion dv4 not booting up, has blinking caps and scroll lock

have you unplugged, remove battery, plug in, reboot? Try another Cord/Charger with the EXACT same power specs. Has there been any damage to the AC jack due to pulling on the cord while plugged in? Verify your DC voltage at cord plug that fits into the AC laptop jack. Have you reseated/replaced the Memory Mods? The CMOS battery? The HDD ? It sounds like a Power issue as it the Cord/Charger/AC/DC Transformer? Hard to say from here without a MultiMeter to verify. Look at HP support: http://h10025.www1.hp.com/ewfrf/wc/documentSubCategory?tmp_task=solveCategory&cc=us&dlc=en&lc=en&product=3860431

AC adapter (Charger) removed from the laptop, remove the Battery. Wait 1 minute then reinstall the Battery.

Post your findings in a Comment.

Regards,
joecoolvette

check out the blink codes here
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01443366&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN

Could be one of several possible reasons. (the most likely is not promising)
Firstly, remove the battey and try it on mains power only, if this works, the battery is so badly faulted, it is causing problems in the laptop booting.

Secondly, remove each RAM module in turn and see if it boots with one ram stick, if it does, you have a defective module

Thirdly, and with HP laptops, most likely, the blink sequence you describe is related to the graphics chip. If the laptop was getting hot before this happened, its a fair bet that the chip on this has unsolderd itself (will need reballing). Google and you'll find the V and DV series which were fitted with the Nvidia chipset, were prone to this and the result of a lot of returns to HP. If it is still under any warrantly, i'd take it back, as this problem is not fixable easily

When HP laptops don't boot but blink the scroll and caps lock lights it usually means there is a problem with the motherboard or RAM. The ram can usually be removed from the bottom of the laptop with relative ease. Before removing the RAM or doing any work on the laptop please make sure that it is unplugged and the battery has been removed. Locate the door pictured below and unscrew and remove it. The ram is held in by two prongs putting pressure on the chip from either side. Push the prongs out and the ram should slant forward, out of the machine. Carefully remove the RAM and clean the connectors gently with a pencil eraser. Carefully put them back in and back between the pins. Place the door back on and screw it back in place. Try rebooting the laptop. If you don't feel comfortable doing this or if the issue is one with the motherboard, and your laptop is still under warranty you may want to call HP. If it is under warranty HP will most likely repair your machine free of charge.

try to boot in f12 format then run windows after prompt.

I am too having a the same problem started 2-3 days back.. Please post the solution anyone have

Sounds like a loose connection if it used to work fine and problem starts after after you taken it apart.

I had the same problem with my hp pavilion dv4 1430 and to fix it I just took out the battery and unplugged it from the power adapter and pushed the power button and waited for a few minutes I put it all back together and started it up and the screen turns right back on.

Hi:
Compaq and Hp are having issues with several models, Go to the HP/Compaqs website, look up your model and see if it is one they are offering free one time repairs on. My friend's dv4 computer was doing same thing, they replaced the motherboard for free, and it took about 2 weeks to get it back.