Who I have the same questioned this topic

(did not find a Moto g6-specific discussion board so posting here)

Moto g6 phone worked great for a couple of months, but about a week and a half ago, it started acting up, powering itself off.   When it would come up, the charge would show just fine (80%, 90%, whatever it was when last accessed).   All the same, I checked my Battery Saver options, screen saver, etc.   It began to get worse, sometimes taking several attempts to get it to power up.   Then it started blanking out in the middle of using it.   I booted into Safe Mode, and the behavior was the same.   Now, it will not complete a boot cycle.   It shows the Motorola splash screen, but seldom gets as far as the "Hello Moto" screen and no longer ever gets as far as my home screen any more.

When on the charge cable, it shows a good charge, and I leave it plugged in overnight.   It starts out showing 100% on its charging screen, but no change in boot behavior.

Followed troubleshooting steps on Motorola's support page - no go.   

Anyone else had this problem?  Any suggestions?