Power button on the remote is the only way turn it on.
You can find the .pdf online by searching “Bose Solo 5 manual”.
If point the remote at it & hold the power button down for 5-10 seconds you’ll here a tone. It’ll turn on automatically when it receives an audio signal. You’ll find that feature in the manual under Auto-Wake. You can literally find ANYTHING by googling it.
Hope this helps.