Battery Full [Q] Charging problem when screen off

Hello everybnody, i'm new on this forum, i got a new device , a spanish brand called Szenio model 50-QHD
Everything works great but i have a problem when charging, when i plug in the charger it shows it is charging and after screen turns off, i turn on screen to see the charging process and it shows : please plug in the charger, like the charger wasn't connected. When i'm using the phone while charging it is charging but when i turn off the screen phone stop charging, i can't understand why, even when phone is off and shows only battery animation, after charging 2% percent stop charging and turns off, pleae somebody help me i don't know what is the problem, i'm using the STOCK ROM.