Although a little late, finally Sprint HTC One M8 also got the official Android 5.0.1 Lollipop, while the Harman Kardon edition apparently still waiting for their turn to get the OTA update, possibly due to the HK edition has a slightly different software.
If you are one of the M8 owners, you should get an update notification at this time. You can download and install it right away unless you have been rooted and currently have a custom recovery installed.
The Android 5.0.1 update contains new firmware version 4.20.651.10 with HTC Sense 6.0. In addition to the Lollipop OS, the update also brings enhanced privacy features, additional search function in the settings and new lockscreen and notification UI which inspired by Google Material Design. The OTA update file size is quite large at around 713MB, but you can download it in just a few minutes on Sprint 4G LTE.
As we’ve mentioned, the OTA update won’t be installed if the phone still rooted, lots of modified system files and have a custom recovery installed. So in order to install the Android 5.0.1 via OTA, your smartphone should be in stock, unrooted and also with stock recovery. You can restore the changes that you have made one by one, or directly via RUU.
Enthusiast users shouldn’t get worried since we can regain root after Sprint HTC One M8 Lollipop update, utilizing the same method, flash a custom recovery again and then flash SuperSU.
If you already rooted, let alone have been managed to get S-OFF, updating the phone via OTA is a last option. Because there is a faster and easier method, like flashing the official stock rooted Lollipop ROM which you can get from Xda and then flash the 4.20.651.10 firmware via fastboot.
So there is no wasted time to revert the phone to stock and then manually regain root access after that.