MTK CPU:
1. Firstly setup the MTK USB driver your pc.( Download MTK Driver)
2. Connect the mobile to pc using USB data cable. Mobile must be switched off and disconnect the battery from mobile.
(itel a13 Firmwaer vartion= A13-W507C-6.0-BD-V021-20180615-RELEASE Download Link ).
3. No need to press the boot key to connect for flash.
4. Browse the flash file from your pc.