Why won't my laptop boot up?

When you upgrade RAM on any computer, not just laptop, the first time that you turn the computer on, it may display some information about a change that you just made to the configuration. This is normal behavior, it just means that your computer is adjusting to a change that you made to the hardware of the computer and, because of that, it is essentially updating the configuration to allow the extra 4GB memory module that you installed to take effect and give the boost that you wanted. It is normal for your computer to restart continously after you installed the RAM. The thing that you did wrong was unplugging the battery while the computer was on. You didn’t make your computer faulty as a result of that. Reboot your computer, with the newly installed memory module, and do not touch anything and let it boot up and do that loop that you mentioned. If that turns out to not be a solution to your concern, please tell me more.

I would try holding the power button for at least 15 seconds, then turning it on as normal. Hope this helps!