3 Lights Flashing, wont turn on. Please Help

I have a 1.5yr old+ Presario cq61 that wont turn on. When running off the battery the front 3 white lights flash on and off 3 times. When running only off the ac adapter nothing. The battery reads 10.5volts by itself on my multimetre but i assume under load it wouldn't be enough to even turn the notebook on? (the laptop hasnt been used in a few months, so maybe the battery is dead & not charging?)



I dont know if its safe to measure the voltage on the ac adaptor where it plugs into the laptop? Just to see if the adapter is working.



If its an internal problem I assume its not worth fixing?



ty



EDIT: this was giving to me so the owners just left it sitting there for a few months, not exactly sure on the health of the battery. Was thinking of buying a new battery, but its probly not going to charge as its an internal issue. Just guessing. I cant download the PDF troubleshoot manual as my slow net cant lol.