Diagnosis
The solid red light usually means it's stuck in a low-power or error state, often after a power surge or a firmware hiccup. It's not receiving normal power-on commands.
How to Fix It
You need to do a full power cycle to reset it. First, unplug the soundbar from the wall outlet. Then, unplug the small power brick from the back of the soundbar itself. Wait a full 60 seconds—go make a coffee. Plug the brick back into the soundbar, then plug the unit into the wall. The light should turn white and it should power on normally with the remote.
If That Didn't Work
Try a different power outlet entirely, in case the one you're using is the problem. Also, check that the remote isn't the issue by trying the physical power button on the soundbar itself after the reset.
Heads Up
Always use the wall outlet, not a power strip or surge protector, when troubleshooting this. Some strips can cause weird power delivery issues with these units.