How can I backup my phone so I can reset or unlock it a diff way?

I have a Samsung Galaxy Note 9 and my phone died and I usually use my fingerprint but I'm not sure if I forgot my password because I've been using that same password for about a month and then it says that it's invalid. I've tried resetting the phone and doing the password again but it doesn't work. I can't power off cuz I need my password for that so I tried letting it die and doing it again, it didn't work. I don't trust the videos on YT so I want to know if I can back it up or reset the password somehow. Also, I have my phone account on my mom's account still, I think, I'm kinda afraid to ask her since she is really mad that I can't unlock my phone and I don't know if Find my Phone is on but I'll try. If there's another trustworthy way, please do tell me.