Lenovo S650 is a great phone and I think it's newer brother, S660, is even better. There are only 2 real drawbacks:
- it has no built in compass (which is really really bad)
- it has very special software, VibeUI on it.
The VibeUI. It can very well be kitkat (yes, they do have official kitkat update now), but you wouldn't know that unless you look at the software version, because they have modified everything. Even settings menu is custom, I hate that. Another issue is that fishy antivirus thingy that keeps bugging me. It could run in background, but instead it's always on status bar. I hate that. I tried to escape it in any way, but there is no support, seems like everyone loves the VibeUI.
Last night I found out there is an AOSP kitkat version that actually works. So i've written a small article how I installed it on my S650, because this custom firmware is published on russian site and while i can somehow read it, i believe there are people that cannot.
First, here's a link to the forum topic that has various firmwares: http://4pda.ru/forum/index.php?showtopic=567114
IMEI backup
It's very possible that you will loose your mobile connectivity because of invalid IMEI error after flashing any firmware. You have to write down both IMEI numbers of your phone just to be safe. You have been warned. Do this first and save the numbers.
Custom recovery
You will need TWRP recovery for your phone. I got it from here: http://lenovo-forums.ru/topic/3499-lenovo-s650-%D1%80%D0%B0%D1%81%D1%88… (or here)
I had ROW version installed already because my phone was ROW.
Firmware
I chose "Google_AOSP by Zver999666", because it was latest that had all features i wanted. It's posted here: http://4pda.ru/forum/index.php?showtopic=567114&st=1380#entry35813841
There are 3 downloads: ROW version, CN version and Root that works on both. You have two options to choose from: ROW ROM or CN ROM, but you have to flash version that your current system has. I tried to run ROW, but I got stuck on a boot loop with coloured dots flying around, never finishing the boot.
ROW TO CN TWRP change
So what i did is, i changed TWRP from ROW to CN by flashing a new one and I also flashed filesystem fix rp_5.5+0.5gb-cn.zip, originally posted here, but the link didn't work so i got it from here: http://lenovo-forums.ru/index.php?app=forums&module=forums§ion=atta… .
It also comes with an instruction: you flash TWRP CN version (2.7), reboot and then flash the format.zip that has been automatically created in root of sdcard.
Then i flashed the rp_5.5+0.5gb-cn.zip mentioned earlier and it was all good now.
Flashing CN version
So yeah, I flashed the CN version, then Root pack and it just worked.
Invalid IMEI
This one has been bugging me from the very first night I got the phone and flashed it. I think i accidentally formatted the wrong partitions or something, but i had to fix IMEI. Apparently it was erased so I had to fix it somehow. IMEI1 is written on the back of the phone, I calculated another IMEI using online calculator (cannot recall which one), because you cannot just provide a random one. I used those 2 IMEI numbers and software called imei_mtk6515 (I know we have MTK6582, but it indeed works) from https://github.com/luckasfb/Fly_IQ255_Firmware_Build/tree/master/tools/…
You have to run it like this: imei.exe <15digit_IMEI_1> <15digit_IMEI_2> MP0B_001
I have linux, but the exe file still works even for me, so apparently it doesn't matter if you have windows or linux.
This command generates nvram file MP0B_001, that you have to put in /data/nvram/md/NVRAM/NVD_IMEI/ . To accomplish this, i used software called "ES File explorer" that has "Root browser" option which allows copying the MP0B_001 and putting it in location provided above.
One more thing: It didn't work for me at first, but i figured out i have to set permissions for the file, 660 (rw rw -).
Reboot the phone and you should have coverage now.