[Coolpad Cool1 Guides, News, & Discussion] vulturext:
Today I will make a guide as complete as possible to guide new user into flashing custom ROM for their Coolpad Cool 1 Dual. This guide as far as I can tell is usable for all C103, C106 and R116 version.

Introduction :

So our device finally got Android 9 in custom ROM development. Unfortunately, to flash Android 9 you need to be on EUI Android 6 Marshmallow. For those who are already on Android 7 you need to rollback to stock EUI to upgrade to Android 9 or else your device wouldn't boot or stuck in bootloop even with full wipe in TWRP.

Preparations :

1. Microsoft .NET Framework 4.7.1 (Offline Installer)

2. Visual C++ Redistributable for Visual Studio 2015

3. Coolpad Download Assistant Setup V1.94_170421.exe

4. Coolpad keys for Assistant ( you need to sign up an account at 4pda to download )

5. Stock EUI18 ROM package for Coolpad Download Assistant

6. Coolpad Driver

7. MiFlash 2015

8. TWRP 3.1.0 by Cuoco92.zip ( you need to sign up an account at 4pda to download )

9. Qualcomm HS-USB QDLoader 9008 driver. ( Windows 10 already has this driver automatically )

10. Android 9 ROM of your choice, of course.

Step 1 : Rolling Back to EUI18

1. Install everything. In the install directory of Coolpad Download Assistant, extract the "Coolpad keys for Assistant" files into main folder. Run Coolpad Download Assistant as administrator.

2. Put phone into bootloader (fastboot) mode. To do this, turn off your phone. Press Vol Down and connect your phone into your PC. The device will boot into bootloader mode with chinese letters and android icon on screen. Check your device manager and it should detect your phone as "Coolpad Android Bootloader Interface". If it didn't detect, make sure you install the driver or try changing USB ports.

3. Extract the EUI18 .zip file into a folder. It should contain 2 files, "init.cpb" and "ROM.cpb"

4. Open Coolpad Download Assistant. Browse to the folder where you extracted both files. First, select "init.cpb" and click the green button in Coolpad Download Assistant. This "init.cpb" will prepare your device to flash stock EUI and wipe everything.

5. After it finished, now select "ROM.cpb" and click the green button to start flashing. This is the main ROM files to install stock EUI18 into your phone. Your phone screen will change into chinese letters with gears icon.

6. If everything went well, it will say upgrade finished without any error message or red letters at the blue smiley screen. You're now back to stock EUI and stock recovery.

Step 2 : Installing TWRP custom recovery to EUI

1. Now that you successfully rollback to EUI you need to flash new custom recovery TWRP to your phone because you now have stock recovery.

2. Put your phone into QDLoader 9008 mode. To do this, turn off your phone. Press Vol Up + Vol Down button and connect to your phone to PC. Check your device manager and it should detect your phone as "Qualcomm HS-USB QDLoader 9008" (COMXX). Your LED should be blinking red if it enter this mode.

3. Extract TWRP 3.1.0 by Cuoco92 in folder. There's a lot of files here so make sure you put it into separate folder.

3. Open MiFLash 2015 and browse to TWRP 3.1.0 by Cuoco92 folder that you have extracted in your PC.

4. Click refresh in MiFlash and if you got all the correct files earlier, it should detect your phone in it identifies by COMXX ( XX is any number ). If it doesn't detect, try rebooting and booting into QDLoader mode or just change USB ports.

5. In MiFlash, select "Flash all except storage" and click "Flash". Wait for the green bar to finish and it says completed.

6. If everything went smooth without any error, disconnect your phone from the PC. The LED should stop blinking.

7. FIRST BOOT AFTER MIFLASH IS VERY IMPORTANT OR YOU HAVE TO DO THIS AGAIN MAYBE FROM THE COOLPAD DOWNLOAD ASSISTANT.

8. While the phone is still turned off, hold down Vol Up and press power button. This should boot your phone into recovery mode. If it boots into TWRP, then you have done everything perfectly. If it doesn't, try repeating MiFlash steps.

Step 3 : Flashing Android 9 with TWRP

1. Backup your images and document from your phone because we will wipe everything.

2. In TWRP, Wipe>Advanced Wipe, wipe everything, system, cache, data. After that, back to Wipe and choose wipe>format data. Type yes and let it format data to erase your device clean and remove encryption to be able to flash Android 9.

3. After wiping and format data, in TWRP, select Reboot>Recovery to reboot into recovery again. This is important because TWRP need to mount the partitions again after formatting the device.

4. At this point, you're now free to flash any Android 9 ROM of your choice.

*no pictures for Coolpad Download Manager steps in this guide. Will probably put them later. (or not because that would mean I have to rollback my already on 9 Cool1 back to EUI and it might brick)