my ASUS X540S sometimes cannot boot without connecting to the power and some times it can boot yet the battery says its 100%. Sometimes when i try to disconnect the power it shuts down and sometimes it stays just for a short time then goes off.
Laptop batteries do not last forever.
Likely, yours is failing.
Be careful about replacing it with a cheaper generic battery.
Sometimes the battery is very closely tied to the laptop for proper operation.
Best to buy a genuine replacement if you can.
I'd generally think it was the battery not putting up the amps, but it could also be a DC/DC power board. Just because it says 100% doesn't mean it's 100 per cent working. I've seen this behaviour in all kinds of devices.
I'd almost always get a new battery first, reason being, it starts fine plugged in with the superior current supplied by the aadapter.
Laptop batteries do not last forever.
Likely, yours is failing.
Be careful about replacing it with a cheaper generic battery.
Sometimes the battery is very closely tied to the laptop for proper operation.
Best to buy a genuine replacement if you can.