MacBook Pro crashes during boot
There most common cause for this error, is a time/date issue.

If you notice the time and date are wrong during the installation, try the following:

https://apple.stackexchange.com/a/166746/164066

There's more info on the error here:
http://osxdaily.com/2015/01/19/fix-os-x-install-errors-cant-be-verified-error-occurred-preparing-mac/