DIAGNOSIS This is a hard power failure. The internal power supply board has likely failed or a main fuse has blown.
FIX Unplug the soundbar from the wall outlet. Wait one full minute. Plug it directly into a known-good wall outlet, bypassing any power strips or surge protectors. Press the physical power button on the soundbar itself, not the remote. If it powers on, the original outlet or strip was the issue.
IF THAT DIDN'T WORK The internal AC/DC power supply is defective. This requires disassembly and component-level repair or board replacement. You need a technician.
HEADS UP Do not attempt to open the sealed enclosure unless you are qualified. The power supply holds hazardous voltage even when unplugged.