Could also be the exact opposite (experienced this with consumer grade electronics based on microcontrollers often enough):
Because of the large capacitors, voltage from the power brick kinda “ramps up” when it is plugged into the wall. The device/its MCU/most specifically its clock circuit however prefers a hard edge of power being turned on, to reliably trigger its power on reset circuit/oscillator.
You can think of it similar to a pendulum/newton’s cradle/metronome - they also prefer one decisive push to get going reliably.
Unplugging the brick for a longer time is still worth a try, but it could also be this.