Our teams are still running Moto G4 Play phones since we haven’t been able to locate control hubs yet. FTC changed the rules to require a minimum of Android 7 this year, but our phones were Android 6 and say they’re up to date and won’t upgrade. 
But I found a workaround! 
You’ll want to do this on a Windows machine.
- Power off the phone (long-hold the power button, tap “Power Off”)
- Press Vol Down while plugging in a USB charger. It should turn on in Fastboot flashing mode
- Take note of the model. The number is on a sticker under the battery also. (Ours was Harpia xt1601.)
- Look for stock ROM for that phone:
- If you have the Harpia xt1601, you can download it from Motorola Moto G4 Play XT1601 Stock ROM Firmware (Flash File)
- Other models are on the home page: https://motostockrom.com/
- Unzip them to a directory
- Open up that directory, and go into the
Firmwarefolder - Double-click on
flashfile.bat - It should flash the firmware onto the phone.
This should help you get unstuck, but I can’t guarantee this will work for everyone (since I’m not there to help you debug it). If you have any questions, feel free to drop them here and I’ll see what I can do. Include details about what you did, what’s happening, and throw in a picture if it’s a weird error.