HTC One M8 firmware collection for different CID/MID | 3.28.401.9

What is firmware.zip?
Firmware.zip is a part of each OTA update from HTC. It contains important part of the firmware like radio, bootloader, recovery, kernel etc.. Why it's important to flash firmware.zip and when should I flash it?
It is recommended to have flashed latest firmware on your device for best modem performance and system stability. Sometimes it's necessary to have latest bootloader flashed because otherwise your device might not work well with new system update. Does firmware.zip contains radio?
Yes, it does contain radio, and for S-ON devices the only method to update radio is to flash latest firmware.zip Why it's important to flash it before flashing custom ROM?
Because firmware.zip contains boot.img (ramdisk and kernel) that will replace custom boot.img from any custom ROM you have. That's why you have to flash firmware.zip first, because otherwise boot.img will be overwritten with stock one.
If you already flashed firmware.zip after flashing custom ROM, just flash this particular custom ROM again. Does firmware.zip contains recovery?
Yes, it does contain recovery image, that's why after flashing firmware.zip you will have to flash custom recovery again, to be able to flash custom ROM afterwards. Can I flash this firmware.zip on any HTC One?
Not if your device is S-ON. To be able to flash it on S-ON device, your modelid (example: PN0710000) and cidnum (example: HTC__001) must match the firmware.zip version you are about to flash. If my modelid or cidnum doesn't match, can I brick my device if I try to flash firmware.zip anyway?
As long as your device is S-ON flashing firmware.zip with non matching modelid or cidnum will result in error and nothing will be flashed, so there is no risk of brick. Do I need to have locked, unlocked or relocked bootloader to be able to flash firmware.zip?
Your bootloader needs to be relocked. If I can't flash newest firmware.zip because of wrong modeid (MID) or cidnum (CID) does it mean I can't use custom ROM based on the latest HTC update?
In most cases you should be able to run any custom ROM as long as hboot update is not mandatory. What if there is no firmware.zip for my MID/CID?
Try to find latest OTA update for your original stock ROM and send it to me. I will post firmware.zip here.

 How to flash
(bootloader needs to be relocked)

1. If you are S-ON ---> Re-lock your bootloader (this will most probably wipe content of your device)
2. If you are S-OFF ---> no need to re-lock the bootloader.
3. Copy downloaded .zip to fastboot.exe location (e.g. c:/SDK/platform-tools/fastboot.exe)
4. Re-name .zip file to firmware.zip
5. Open command prompt
6. Boot your device in fastboot mode (vol down + power ===> fastboot)
7. Connect device to the PC
8. In command prompt cd to fastboot.exe location
9. Make sure you have correct modeid and cidnum (type: fastboot getvar all)
10. Type: fastboot oem lock (if your device is not relocked yet or in case it's S-ON)
11. Type: fastboot oem rebootRUU and wait for device to reboot
12. Type: fastboot flash zip firmware.zip and wait for process to complete
13. Sometimes flashing for the first time doesn't work, so flash firmware.zip again just to make sure.
14. Type: fastboot flash zip firmware.zip and wait for process to complete
15. Type: fastboot reboot
16. Unlock your bootloader and flash custom recovery if you are going to use custom ROM.

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Posted by: Mr. Cheang Sovan
Tel: 015419789 / 093354161
Note:  I'm not responsibility if something went wrong or your phone was broken during practice this method. Do it in your own risk.