Make sure before this step tat the device has more than 50% battery. Step 2: Connect your device to your PC using a USB cable. Step 1: Download the firmware in EXE format for your HTC device on your PC (that's zipped for convenience).
Once you see a red triangle, hold down the power button and tap vol up once, and then release the power button. Boot back to aboot (hold power and vol up until the screen goes black, and then while still holding power slide your finger down and hold vol down until aboot comes up). Once its done, it will try to boot up, but will just bootloop. Once in download mode it should automatically find the file, and prompt you to press volume up to flash it. Use volume keys to navigate to download mode and select with the power button. Boot to aboot (power off phone, hold volume down and power at the same time). Place file on fat32 formated external sd card in no folders (root). Rename file to exactly 0PJAIMG.zip (PJAIMG.zip). Check MD5 sum and make sure it is correct. Once it’s done your HTC will automatically reboot. Step 9: This time installation will complete and your device will have the firmware installed.
You have to be in RUU mode (see step 6 above), and then re-flash the ROM ZIP file again (see step 7 above). It could be: “pre-hboot update: please flush immediately”. Most likely, you will get an error at the end of the installation. → If your ZIP file is not rom.zip, then use the name it got in the command above in place of rom.zip. Step 7: Flash the ZIP file with the command given below (you can copy paste): Issue the following command in the command window: Step 6: Now bring the device into RUU mode. For this, simply double click on the command prompt file in your adb folder. Step 5: Once the device is properly recognized on the PC, open a command window inside the folder where your firmware. Doing a PC restart is a good thing too after installing drivers. Connect using USB cable again thereafter.
In case your PC fails to recognize or detect your HTC device, then you need to install or re-install HTC drivers. Make sure you have installed HTC drivers. Step 4: Connect your device to the PC using a USB cable. Step 3: Boot your HTC device into Fastboot mode (or download mode, for newer HTC devices). You must have htc_fastboot file in this folder. Extract this into adb folder for the purpose of this guide. Step 2: Download ADB and Fastboot drivers.
For ease, rename this file to rom.zip (be sure to rename). Step 1: Download the firmware file in ZIP format for your HTC device and save it on PC. For installing RUU EXE file, see method 2 below, while for RUU ZIP file, see method 1. Note that HTC firmware (RUU) are mostly available in two formats: EXE AND ZIP.
The HTC One M9 is a good Android phone with 2Ghz Octa-Core processor that allows run games and heavy applications.