Sony Dock Power Issue. Power On Green lamp flashes in three sets

This is an iPod/iPhone/iPad dock from 2012. I only want to use it for Bluetooth and Audio In (3.5mm). I do not need the iPod dock feature.

Sony Personal Audio Docking System RDP-X200iP

When I power on, Green power icon lamp lights steady for two seconds, then the lamp flashes in sets of three. Left alone, unit will self-power off.

Pressing the Audio In or Bluetooth or iPod button and then powering on will have the respective lamp light for a second, then go out. Power lamp then behaves as described.

Verified all connections in the DC IN 20 V are tight. Reseat all connections. Tried different outlets. I have tried a Bose DC IN 17 V in supply, with same result.

Contacted Sony chat support. No suggestions. Emailed www.unitedradio.com - the Sony authorized repair. Unit is too old for them.

^{^^^}^^

Sony Personal Audio Docking System RDP-X200iP
https://www.sony.com/electronics/support...

AUGUST 2012

Speaker
Woofer: Approx. 76 mm (3 inches) dia. × 2
Tweeter: Approx. 25 mm (1 inch) dia. × 2

Input
AUDIO IN jack (ø 3.5 mm stereo minijack)
Impedance: 50 kΩ
Average input level: 245 mV

Power output
20 W + 20 W (at 1% harmonic distortion)

Power source
Rated external power source: DC IN 20 V (with supplied AC
adaptor (AC 100 V - 240 V, 50 Hz/60 Hz))

Dimensions
Approx. 356.0 mm × 168.1 mm × 155.8 mm (w/h/d)
(14 1/16 inches × 6 5/8 inches × 6 3/16 inches)
(incl. projecting parts and controls)

Mass
Approx. 2.2 kg (4 lb 14 oz)