I have a Dell laptop Inspiron 3521 bought 18 months ago. I used it just a few times at first.
Battery is OK. (OS must be Linux Mint or Windows 8, I don't remember), but last time it was working)
Now I try to use it again but it doesn't boot,The fan starts to run then the laptop shuts down right away (screen stay black), then there is a regular beep (more like "tap") every 2 or 3 seconds approx. Last time after 21 beeps I long pressed the start button to stop it.
As I have another Inspiron 3521 which works, I changed the hard drive.....same problem.
It has been in my car when I moved, maybe it got hit, I don't know.
Could it be the coin-cell battery? motherboard?......