A) Remove all electrical sources; The AC adapter (Charger) and the Battery.
B) Obtain a multi-compartment container for the screws you will remove. There are screws which look alike, but aren't. You won't realize the mistake until you have the screw in halfway, it is then stuck, and CAN'T remove it. Gives you a warm fuzzy feeling all over.
You can use a clean egg carton in a pinch. Label each egg holder for what area the various screws came out of.
C) Suggest you buy, and wear an ESD wrist strap. (Electro Static Discharge) They cost from $3 to $8. The area you are going into is relatively safe from static shock, as there are no hardware components that are nearby, and prone to Static shock, BUT, it never hurts to be safe.
Static WILL fry out (Short Circuit) the hardware components of a computer, (Laptop or Desktop)
You probably won't see it, or feel it.
Connect the alligator clip to a good ground source. I connect to the metal frame of an empty desktop computer case.
D) I don't find a Service and Maintenance Guide on HP Support, but the information from this link should do very nicely,
It's a dv5 series, but you'[ll find it crosses over to your dv4 series quite well.
Scroll down the page.