Check the charger if it’s working or not.
This can be divided into two types -
# Software failure
# Physical failure
Software failure might happen when you have installed glitchy software the device might fail to turn on. Simply go to recovery mode by pressing the Volume UP + Power button together and delete or factory reset from options available.
Physical button failure also leads to a [link|https://blucellphones.us/fix-blu-phone-that-wont-turn-on/|device not turning on]. In such case there is really a little you can do.
If it still doesn’t work then there is nothing you can do really, except buy a new phone.