Have mtk phone with corrupted IMEI no problem now you can do it easily within running phone as now MT65xx.apk can do the job easily. Just download apk put in sd card and install it tap to lunch and from interface you see it will ask for imei input for dual sim as well as single sim.
Download MTK65x.apk to fix rewrite imei of mtk china phones.
Note : Supports MT6577, MT6513, MT6515, MT6575, MT6517 are yet know but if it work on yours and not listed here tell us in comments and will add here to help other to find write tool.
Free Download Link
Note : Phone must be rooted follow guide below to root mtk phone.
IMEI Repair Apk (MTK65xx-imei_EN.apk) is an Android app used to fix IMEI number on MediaTek devices. Download this app and fix IMEI issues on your MediaTek Android device.
Warning: By no means, we encourage to use this app for illegal purposes. This app is intended for educational purposes only. We are not responsible for any illegal use.
Real IMEI Changer (for MTK Phones) (ROOT required) App
This application make real change for your imei ,Not masking the imei or using fake one , it change globally the imei by new one .
it’s better to make backup before you begin the change if your imei are already exist and valid.
Note that in more countries , the change of the imei are illegal so you will use this application at your own risk , Also this application help you to solve the problem of invalid or null imei and return network to your phone
this application tested for more MTK phones , so if it work for your model write in comment the model of your phone .
requirements :
1- root required.
2- xposed framwork not required.
3- reboot to see the new imei
this tested for this models MTK67XX and MTK65XX and it work correctly so choose your model before you begin changing imei.
after you finish imei change check new IMEI by dialing *#06#
https://droidurdu.com/easy-one-click-auto-root-mtk6589-phones/
https://droidurdu.com/install-recovery-root-mtk6592-mtk6582-mtk6589/
https://droidurdu.com/mtk-6589-root-android-phones-easy-steps-guide/
Go here to fix imei of china mobile via pc