You are missing one line, there should be TWO lines in /etc/crontabs/root so add it back:

*/1 * * * * /usr/sbin/logrotate /etc/logrotate.conf 2>&1 | logger -t logrotate
0 0 * * * /usr/sbin/bos_upgrade_at 2>&1 | logger -t upgrade

Stop mining with /etc/init.d/bosminer stop
But this will ramp up the fans for protection, so also edit /usr/sbin/bosminer_monitor.lua

Search and replace fan_set_duty(i, 100) with fan_set_duty(i, 0)
Some fans don't like it to be set to 0% (they would spin to 100% instead), in that case try higher values until you find the min one.

Then your added lines should look something like this:

0 11 * * 1-5 /etc/init.d/bosminer stop && sleep 300 && /etc/init.d/bosminer_monitor stop && sed -i 's/fan_set_duty(i, 100)/fan_set_duty(i, 0)/g' /usr/sbin/bosminer_monitor.lua && /etc/init.d/bosminer_monitor start
0 14 * * 1-5 /etc/init.d/bosminer start && /etc/init.d/bosminer_monitor stop && sed -i 's/fan_set_duty(i, 0)/fan_set_duty(i, 100)/g' /usr/sbin/bosminer_monitor.lua && /etc/init.d/bosminer_monitor start

Yes, your first * is wrong, that would make it run every single minute, so no, you only run it at minute 0.

The sleep 300 is critical for the x17 family, it is meant to cool down the boards before stopping or slowing the fans. You may shorten the number of seconds if you use the S9 family.