Device went on powersave and never came back on

I purchased this Klipsch R4-B soundbar in 2016. It’s power adapter is plugged into a Cyberpower 1500AVRLCD UPS that is plugged into a correctly wired and grounded 120V receptacle. I have had no issues with this soundbar, until a week and a half ago.

My wife was watching TV on Saturday morning and we stopped to fix our lunch. I assume that the soundbar went into powersave mode, as it usually did after a certain timeout of inaction. When we came back in, we attempted to power on the soundbar, but nothing happened. I removed the power adapter from the wall and the soundbar and left unplugged for 30 minutes. Plugging back in still did not resolve the issue. That night, I left it unplugged from both optical interface and power, as well as unplugging the power adapter from mains, until the next morning. I reinstalled and still will not power on.

I tested the power adapter with my multimeter and it seems to be working fine, putting out 18.4V DC when it is spec’d for 18V. I dissassembled the unit and the circuit boards *look* fine, no scorch marks or outward signs of bad components (caps are not bulging, no leaks on caps, etc). I opened a ticket with Klispch Support over 10 days ago, but have not received a response.

Anyone have any good tips\techniques for me to effectively troubleshoot this issue?