If CM has implemented it correctly,
dmesg should have 2 copies. One current and one from last reboot. You'll have to find where your dmesg copies are located. Try with:
find / -iname "*dmesg*"
Being root when using
find is always an advantage.
EDIT: The other option is to look at the kernel messages. They are called "kmsg" and can be found in:
But these are special files, so in order not to block your terminal when reading you have to use cat like this:
cat /proc/last_kmsg |less
and you probably need to be root. This is not always present or updated, so you may need to change the contents of this file
/sys/module/printk/parameters/always_kmsg_dump from "N" to "Y".