Before you upgrade to 3.6 using local update, you need to check in your Flash the firmware version:
How to check it setting>phone>build number (see the version on Vx.x)
Q: Have you rooted your Flash?
Result: unroot your Flash first
Q: How to unroot it?
Q. Your last firmware version, 2.9, 3.1, or 3.2?
A: My firmware version 2.9-3.1
Result: Don't update locally to 3.6 with partial update (update.zip w/ 286 MB), update it to 3.2 first then go to 3.6 through FOTA or locally.
Q: My firmware version 3.2?
A: you can upgrade it to 3.6 through FOTA or local update using (update.zip w/ 286 MB).
Q: My firmware 3.2, but I have Error, No Command or damage when unzipping package during FOTA?
A: Download the 3.6 package and upgrade it using Local update. Move the package to the SD card root.
(notes: using local update you have to put it in SD CARD root, don't put it in internal phone storage).
Q: How to upgrade using local package?
A: Setting>About phone>wireless update> (touch three dots in upper right corner)> local update > (choose the package, get a cup of coffee and wait for the process.
Q. My Flash is Error and showing green robot dies, bootloop, No Command, restarting itself after I upgrade it.
A. Call 911 . . . hehe . . just kidding, Do a Flash Recovery.
Q. How to do a Flash Recovery?
A. You can choose several ways
1.Flashing stock ROM firmware Flash 2 using SP Flashtool via your PC. Firmware version 2.9
2.FLASH 2 RECOVERY + UPDATE SW v3.1-151031 via SD CARD
After you downgrade to 2.x, update it to 3.X first before go through 3.6 version.
3.Force Upgrade Recovery to 3.6 follow this tutorial (This is full upgrade so it will wipe all your data):
Download the 3.6 Stock Rom Here http://bit.ly/Flash2v3-6
a) Turn off your phone
b) Long press Power Key and Volume Up Key
c) Select Recovery Mode
d) When "No Command" messages appear, Press Power Key and Volume Up Key two times
e) Into Recovery Mode by Volume Up Key
f) Select apply update from sdcard
Q: My phone is still running but I have error on my Flash. If I do a Flash Recover, all my photos with my lovers will be accessible later?
A: No, it won't. Flash Recovery (1-3) will be deleting all your files in internal phone storage and restore the system to the new one.
Q: So, what I have to do with my files and photos?
A: Do a Backup and Restore before you flash it using backup application available in Flash 2. Or you can using cloud storage to backup your photos and files such as, dropbox, google drive etc.
Q: I forgot to backup my photos with lovers and I lost all the photos
A: Go find a new backup lovers and create new photos
Q: Where I can find new backup lovers?
A: You can find it in http://community.flash3c.com/c/community/introductions
Q: I still don't understand what are you talking about
Don't worry we're here to help