Using this tutorial you can upgrade your phone software to the 36P firmware. Compared to the older firmwares it does not have the calculator bug and it is a little bit faster in menus. It also include the increased volume patch

Required software:
1. RSD Lite 2.5 or higher version
2. Drivers (in case you didn't installed them yet)
3. The 36P firmware (download is below)
Download 36P firmware HERE

Tutorial:
1. Turn off your phone. Hold the "Voice Key" and then press the "Red Key" to go to bootloader.
2. Unpack the zip archive. Start RSD lite. It may ask for drivers - install them
3. Select R564_G_12.00.36P_flash_dev_flash.shx and flash it. That is the BP part and it is 33P (this is not a problem)
4. After that flash is done you will have to start flashing the AP part (36P.sbf). Before you continue you will have to prepare for some extra steps.
a) First you have to choose which language pack you wish to use. You have two folders - Chineese and Russian. In the Chineese folder you have 4 .smg files, which will make your phone into LP 0615, which is English + Chineese. The Russian folder contains 5 .smg files and it will make your phone with 02DE, which is English + Russian + Suomi + Polski + Eesti + Latvian.
b) Here is the most important part before you proceed - you have to copy (Select, then Edit > Copy) the .smg files that you choosed in step a) and be ready to paste them into the folder where you unpacked the 36P.sbf at any time. Go to the next step
5. Select the 36P.sbf in RSD Lite and click "Start". The "Extraction" of the files will begin. You have to be fast here - wait until the extraction become 100% and RSD Lite starts to flash your phone. Then very fast go to the folder where you extracted 36P.sbf (you will see a lot of .smg files are extracted inside) and paste the files that you copied on step 4. You must OVERWRITE the .smg files that will be flashed
6. Now wait until the flash finishes. At the end you will see "Flash Failed" - no worries, everything is under control
7. Unplug the phone, remove the battery, plug the battery back and start the phone. You are on 36p!