MacBook Air 2017 doesn't power on without Adapter

[Bijolak]

Hi guys,
Hope you all doing good, I have a problem with my MacBook air 2017 which I had its Thermal paste changed and before doing all that I unplugged the battery while it was off and off the adapter, I did my work and replugged the battery, and closed the lid, it powered up normally and I used it for some days but one day after shutting it down the next day it wasn't powering up on battery, I plugged the adapter and it started and in the settings, it says power source is the adapter, when I open the laptop and unplug and replug the battery it turns on but after shutting it down it won't turn on again. Do have any advice on to how resolve the issue? current macOS is big Sur.

Thank you in Advance!

 

[zoom25]

Do this test. Turn it on as you currently can and leave it on charging until it's fully charged, so for a few hours just to be sure. Then unplug the power adapter and use it off battery alone. Continue to use it as you were using it. How long does it stay on? If it turns off rather quickly, then it's an aging battery issue and it will need to be replaced. However, if it seems to stay on for a decent time and the issue remains that the laptop cannot be turned on from battery, it may be time to take it to Apple.

Hopefully, it's just a battery issue. Other than that, reset NVRAM, PRAM, and SMC. I always hit those up whenever diagnosing an issue.