A USB stick would be simple & quick.
To get some help about your specific issue some data about the update process (the update log of the update before your system crashes and a boot error log after the update) & more detailed info about the hardware of the machine in question. Check out this post:
and please leave the output of:
inxi --admin --verbosity=7 --filter --no-host --width
in this thread, (it will only output generic machine information)
What method did you use to install the driver from nvidia site?
Have you tried using the default gui or terminal method first?