Laptop not charging while turned on the battery isn't lasting as long

Sounds like a depleted battery; when a battery has been drained to zero some cells are damaged, and the battery Smart chip is preventing the battery from being charged again. Run a Battery Report in Windows and see if it charges to full (designed) capacity. in the command prompt type this: powercfg /batteryreport. If the battery is still good (<3-years old) try the needle and pinhole reset if you have a reset pinhole in the back of your laptop:
Check if there is a small pinhole in the back of your laptop (with a battery symbol) and stick a pin (SIM card retrieval tool) in that hole till you feel it click (micro switch), keep pressing the pin for a few seconds. This will reset the battery. If no results try this:

Power drain + CMOS reset: Open the back of the laptop and disconnect the battery cable from the motherboard. Locate the CMOS module (with 2 twisted wires Red and Black) and remove the coin battery. Shorten the +/- contacts inside the CMOS capsule for 2 seconds with a bended paperclip and put the coin battery back with the + sign facing up, close the CMOS capsule. Check the seating of the RAM models (unseat and firmly reseat). Next, press the Power Button on the keyboard for 10-15 seconds after that reconnect the battery cable to the motherboard. Close the laptop, plug-in the adapter and try to boot.

You are welcome, glad you had it fixed.