My galaxy s9+ tried to install the latest update yesterday evening and has been stuck in a loop since. At first, the phone would only update to 35% and then be stuck on that screen. I tried the volume down+power trick to stop the update and that is what started the reboot loop. The screen will light up with the Samsung powered by android logo and then it will turn back off and then repeat. I tried stopping that by pushing the volume up+bixby+power button. That caused it to try and update again. It will install up to 28% and then stop and go back to the boot screen. It will repeat the attempted update 2-3 times before going back to the boot loop. I've tried letting the battery die. That didn't work. I tried charging it and nothing. Only one time when it tried updating did it pop up with an error screen. The phone has not been physically damaged.
It can't get to the Android Recovery menu because the phone just restarts when its gets to 28%. So the solution you given also didnt work
Hey there, I see you have also sent us a private message regarding this. I will follow up with you there.
You my need to reflash stock firmware. Make sure you use Sm-g965x where the x is the carrier. Firmware is model and carrier specific, be careful.
Load the firmware into odin on windows, then plug in your phone and install drivers. Once in has recognized the phone, put the phone in odin mode and start flashing. This should fix the bootloop