first off there is no such thing as a DV4, sorry!!!!
dv4-1000, 1280,1300, right?,. it's 10 old, the battery is that old is no good, the dash matters too if present (details do)
or is it a DV4000
, 13 years old not 10 .??? why not post the full model and p/n off your PC service tag so i can show you matching manuals to read and follow, ok?
THE AGE MATTERS AS DOES REAL MODEL NUMBERS!!!
that is blink code, try to learn how to read them , counts them.
here is a list of tests, simple. to harder.
1; Remove that old big battery 10 years old , it shorted.
2: run on AC power only. in fact can do this forever.......
3: next is the fan working? fan is next and now, does it?
4: flash codes, count them and report them, easy no?
5: the coin cell is next , it is 10 years old that too is END OF LIFE
why not replace it too ,now even if good, to avoid problems later, ?
My answers are for DV4000 only not the DV4-1000 and up vast series of laptops. vast versions of them...
the coin cell , HP name RTC battery, all die at 5-7 years old.
yours is well beyond that. ok?
lets do chapter 5 covering just that now.
here it is, pg 5-20 pdf page 126
we take it it out if lower than 2.9v (a dmm meter is cheap)
we replace it, 3.3 is normal when the fall to 2.9 (think cliff)
they fail fast and the BIOS GOES NUTS,
in fact the PC can be totally dead.
see the manual , if wrong next time tell full service tag data.!!!
that caps lock flashing are codes, learn to count them
my wild guess is it is the code for BIOS NVRAM corruption.
the cure is posted here over 1000 times.
and a million times at HP.com real, we are not HP.