Answer: This can happen after a flash stock operation. The solution is to factory reset in stock recovery. If you want to preserve userdata you can try just wiping cache. If you have already installed a custom recovery, you can use the toolkits Advanced Utilities > Fastboot Flash > Recovery > Restore Stock Recovery.
If a standard factory reset doesn’t work, try flashing stock again.
If the issue still persists you can try ‘advanced utilities’ > ‘fastboot format’ > and then have it format system and userdata – then use “soft brick mode” to “Flash Stock + Unroot” one more time (if needed).
Answer: Having no recovery at all is highly unlikely unless you deliberately issued a fasboot erase recovery or fastboot format recovery command. Chances are you are confusing the stock recovery prescreen for an indication that recovery is missing. This is understandable because the stock recovery prescreen is very misleading. It is a picture of an android on its back with an open chest and red exclamation point hovering above it. Do not be alarmed.
Quick Tip: The dead android guy is just the stock recovery prescreen.
To bring up the stock recovery menu:
While holding down Power, press Volume Up.
Now you can navigate with the volume keys and select with the power button.
So to reboot the device simply navigate to reboot system and press the power button.
The key combination to bring up the menu may not be identical on all devices. If its not working to bring up the menu try simultaneously pressing all three buttons (Vol Up, Vol Down, & Power) at the same, and repeat this a few times until it works.
If you want custom recovery (either TWRP or CWM), then you can easily flash it with the toolkit:
Answer: If you are ever experience unexplained complications with your device, need to upgrade/downgrade, or need to restore it back to the way it was when you first bought it, then make use of the “Flash Stock + Unroot” feature.
To avoid complications enable Force Flash Mode (recommended)
If you want to avoid a data wipe, enable No Wipe Mode (only should be used for incremental updates).
If you have complications, Disable ‘No Wipe Mode’. Backup your important files first and do a clean flash (the device will be completely wiped including sdcard content).
Quick Tip: ‘USB Debugging’ is not required for restoring your device.
If you device is bootlooping or can’t boot up, use “Flash Stock + Unroot” with the “Soft-Bricked/Bootloop” option and follow the onscreen instructions for manually booting your device into bootloader mode and restoring your device.
If you plan on returning the device, after your flash stock you can re-lock it as well with the OEM Lock button.
Quick Tip: Re-locking the bootloader is not required for receiving OTA updates.