I myself own a Lenovo A390 and I have rooted, installed recovery and deodexed using these software tools, without any pain. And I assure you, it will be extremely rare that anything can go wrong. And you don't need a computer to root or install recovery-yes, you can do it on your phone itself.
But let's get some things straight:
1. Rooting/installing recovery voids your warranty.
2. If you're not using a Lenovo device or a device that runs on a MediaTek processor, I recommend that you search for a version of recovery appropriate for your processor.
3. The chances of damaging your phone using these tools is [I]extremely rare, trust me[I], but in case anything goes wrong, I, OR THE DEVELOPERS OF THESE TOOLS, OR XDA-DEVELOPERS WILL NOT BE RESPONSIBLE FOR ANY INTERNAL/EXTERNAL DAMAGE TO YOUR PHONE.
How to root your Lenovo a390:
1. Download Framaroot: http://forum.xda-developers.com/show....php?t=2130276 Note: Framaroot may not work on all Android devices. Please see compatibility list in the link.
Framaroot is an Android app created by XDA user alephzain. It allows you to root your device directly from your Android device-please click on link above to view full compatibility list. Download and Install this app. If it says "Installation blocked", go to your phone's Settings>Security and tick the "Unknown Sources" box. (Believe me, there are n00bs )
2. Open Framaroot. For the a390, there is only one exploit-Boromir, since it's a Mediatek powered device. Select Boromir.
3. Now you see two buttons: Install Superuser and Install SuperSU. You need to select only one of them. Framaroot will then root your device and install Superuser/SuperSU. (Superuser/SuperSU are apps which control root operations on your device ie. ensure no app uses root features without your permission-it is a MUST.)
The choice is up to you, but I'd recommend Superuser since it's like the Industry standard of rooted Android phones.
4. Reboot your phone. You'll find Superuser installed. Open it, swipe from left to right to access Superuser settings. The su binary is outdated and it'll appear in a red font. Tap it to update su binary.
This is proof enough that your phone is rooted, but if you really need to see, here's one more step.
5. Install Root checker from Google Play Store: https://play.google.com/store/apps/d...krim.rootcheck
Run this app, and if your phone is rooted, Superuser will come up automatically asking you whether Root Checker should be granted permission- press Yes and root Checker will deliver the result.
That's it-congratulations, you've rooted your a390 without any pain. Now you can flash a recovery, install Busybox, overclock your phone, get rid of the dumb apps Lenovo has included with the a390.... Enjoy!
How to install a recovery
Now, there are two recoveries that rule the Android universe: ClockworkMod Recovery (CWM), and TeamWin Recovery Project (TWRP). The bad news is, neither is officially available for the Lenovo A390 or most of MediaTek devices. But where there's a will, there's a way- and some anonymous Android developer has created TWRP recoveries for the entire Lenovo smartphone series. <salute to the unsung hero> I used one specially customised for the A390, and it works fabulously.
First of all, ensure that your phone is rooted. If not, read the tutorial above.
1. Download this recovery.img file from this Google Drive: https://drive.google.com/file/d/11-V...it?usp=sharing
2. Install Recovery Tools-Flasher from the Google Play Store: https://play.google.com/store/apps/d....recoverytools
3. Now press "Flash Recovery" button, it will open a file browser. Select the recovery.img file you downloaded from the file browser.
4. It should show a dialog box that says Flashing done. Press OK to boot into recovery. Press OK, and you'll see the TeamWin IdeaPhone load screen-and boot into TWRP.
Congrats, you've installed the recovery. Now you can install custom ROMs on your phone and backup your phone's kernels as protection against troubles. Enjoy!
How to deodex your phone's ROM
Sadly, you cannot do this using your phone. You'll need a Windows PC for this process, a good Internet connection as you'll have to download large files for this process, and plenty of time.
Here's a good XDA Developers Tutorial on how to deodex your rom, complete with step-by-step explanation and screenshots: http://forum.xda-developers.com/show....php?t=2374008
There you go. If you followed my tutorial completely, you are now a proud owner of a rooted, recovery-flashed, deodexed MediaTek device/Lenovo A390.
Please hit Thanks button if my post helped you.