What you can do, with some extra steps, is have Home Assistant installed (and have a Home Assistant server, I guess!) on the phone and use a smart power switch that's also associated with Home Assistant.

The phone's battery can be reported to Home Assistant, where an automation can be triggered to turn off power to the phone when the battery gets above a certain percentage and turned back on when it goes below.

Not the best solution, but certainly an alternative from messing around with trying to get the phone to work without a battery.