Hi kihapet !
You've already asked for help to developers. You gave them the technical specifications of your phone ... but you didnt write the same technical specifications here on Chinaphonearena. Here what you wrote to developers : "Hi Guys. I have the innjoo Fire Pro with the MT6735 2GB of RAM and 16GB space and running Lollipop 5.0. I have tried in vain to root the phone Kingo Root, King Root, Shuame all fail. What other option can I use?" :-)
Well, follow carefully the next steps :
1) At first I strongly recommend you to download the stock ROM from the official site :
[Only registered and activated users can see links Click here to register]
2) And then, I suggest you to download the TWRP.img from the next link :
[Only registered and activated users can see links Click here to register]
3) Now, you have to rename the downloaded twrp.img to "recovery.img"; after that, you will have to overwrite the original stock "recovery.img" with the twrp.img (renamed).
4) And then, flash the modified stock ROM with SP Flash Tool; you will find SP Flash Tool at the next link :
[Only registered and activated users can see links Click here to register]
5) How to flash it ? Watch carefully the next video-tutorial
6) Now, you have to install Mobileuncle; please read carefully the next thread :
[Only registered and activated users can see links Click here to register]
7) Now, you have to download Download "UPDATE-SuperSU-v2.46.zip" at next link:
[Only registered and activated users can see links Click here to register]
8) Copy "UPDATE-SuperSU-v2.46.zip" on your microSD.
9) Tap on Mobileuncle and tap on "into recovery mode". You will enter into TWRP custom recovery.
10) Tap on "Install" and choose "MicroSDcard"; then tap on "UPDATE-SuperSU-v2.46.zip" and "Swipe to install". At the end of the process tap on "Reboot-System".
Please keep me update about the situation.
Regards :-)