That is weird indeed. I can only imagine inxi trying to get some information about your hardware and cannot get it to the point it crashes.
That reboot and shutdown leaves you without a working keyboard when you turn on the device again is pretty weird. Or did you mean it does nothing and does not react on key presses after you press shutdown or reboot?
All in all I assume the system has problems with your hardware. Can you tell us which hardware you have?
Maybe installing a new kernel from debian backports can help you as it usually supports a bit more modern hardware.
To do so you need to go to synaptic and software sources and make sure that the debian buster backports repo is marked active. Reload the package list in synaptic and install the linux-image-5.4.0-0.bpo.2-amd64 package.
After that try rebooting and see if it works better with the new kernel.