Reboot Loop on iPhone 11 (current software)

Hello! So my sister's iPhone 11 is constantly rebooting. We are trying everything but I just don't know what we're doing wrong.

How it went down:

Sister goes to take a photo on her phone. Phone, mid-photo, acts like it dies and shows the Apple logo. We plug it in to charge it, but notice that the screen is just the Apple logo blinking on and off occasionally. After some research, we find out its the reboot loop glitch. I start doing some research, and the reset method (press upper volume, press lower volume, then long press power button for at least 20 seconds) doesn't work at all. Tried multiple times and this phone just doesn't seem to recognize it. I even tried the reset methods for other versions of the iPhone just to see if it'd work, no luck though.

Anyway, we plug it in to a computer and after 30 minutes, it finally recognizes the phone and puts up a message saying that the phone has to be updated and/or restored to fix this. The phone stops forever looping at this point, but its not playing music or videos and lagging occasionally. We also see that the phone had reached capacity in storage on the iTunes summary, so we think this is a storage issue. We delete 80 GBs of videos/photos as fast as we can while the phone works. We then try to update it, and the phone is doing well until halfway through, where the reboot loop starts again. Looks like it was able to extract the software, but when it got to install it, that's where it messed up. Stayed stuck like that for another 30 minutes or so. Tried all the fixes I could find. Finally gave it some time and it finished the update. It successfully updated to the newest software. It let me on the phone for maybe 10 minutes, working beautifully, but it's started up the reboot loop again, and I can't even get the computer to recognize the phone this time so we can just restore it. I am using official apple cords, and have tried multiple to see if its a cord issue.

Any advice? Reset methods still aren't working, I can't get my computer to recognize the phone so I can restore, and I'm trying every obscure method I can find (there's even a YouTube video saying to massage the phone, and, well, I'm desperate).

Thank you so much for your help. I am at my wit's end.