if you're using a carrier such as Vodafone or any other Sim carrier, only use the first Sim as the second Sim is not functioning currently.
If you get caught in a bootloop, hold the volume up key and power key until the device turns off. That should fix it. If not, proceed to boot to recovery, wipe cache partitions and factory reset. Then, flash cm 12 rom followed by gapps and reboot.