CyanogenMod 12.1 Nightly is based on the stock Android 5.1 Lollipop OS, which means users can experience stock Lollipop features on their HTC One Max by installing this ROM. In addition, users can get fast performance and CyanogenMod features like the theme engine and revamped material Design user interface on their phablet. Today’s guide shows you how to update your HTC One Max (Global GSM/Verizon/Sprint) to Android 5.1 with CyanogenMod 12.1 custom ROM. However, your phone must be rooted and latest version of custom recovery (CWM/TWRP) installed.

Note: Before you get start, keep in mind that CyanogenMod 12.1 is a nightly build, which means the ROM is not completely stable. Though most things are work well, still there are a few problems remaining, so the ROM may not be used as a daily driver. Important: This process will wipe your device, so backup every important file on your One Max. Also, make a Nandroid backup of current ROM from custom recovery.

Update HTC One Max to Android 5.1 with CyanogenMod 12.1 ROM

  1. Download the CM12.1 firmware zip file for HTC One Max GSM [HERE], Verizon [HERE] and Sprint [HERE] and move the firmware zip file to your phone’s SD card.
  2. Download Gapps [HERE] and move to your phone’s SD card.
  3. Now, boot your phone into recovery mode. To do so, power off your One Max, hold down Volume Down and Power buttons together for some time.
  4. From recovery, make a full system back up (Nandroid backup). This is important as it let you restore your stock ROM, if anything went wrong after flashing the custom ROM.
  5. Now, do a full system wipe from recovery. Select “wipe data factory reset”, “wipe cache partition” and “wipe dalvik cache”.
  6. Now, go back to the main recovery menu, select “install zip from SD card” and “choose zip from SD card”.
  7. Choose the CM 12.1 firmware zip file and install it. Repeat the process for Gapps.zip file as well.
  8. Once the installation process is completed, reboot your device. From recovery, choose “reboot system now”. Note: It will take little long time for the first boot. Once your One Max booted up, setup your new Android 5.1 Lollipop OS and enjoy! (Source – Flyhalf205)

Troubleshooting

  1. If your phone gets into the boot loop sequence (stuck in the welcome screen), boot your phone into custom recovery, perform ‘wipe cache partition’ and from ‘Advanced’ option perform ‘wipe dalvik cache’.
  2. If above procedure is not helped you, follow the above installation instructions again.