See the Moderator's post right above yours. If your problem is NOT that your device is stuck on the Alexa screen, why not start your own thread. Add some details like what device, and what are you trying to do.
NOTE: I do NOT speak for or represent Amazon in any fashion. This is a customer to customer forum.
Disclaimer: I have examined any sites I provide links for and have determined them to be safe but I make no promises about safety, content, ads served or anything that might make you clutch your pearls in horror. Use discretion clicking on links provided by total strangers such as myself.
Fire 10 7th Gen. See if the Fire is in Show Mode. Pull down to access the settings (wifi, airplane, etc.) At the bottom there is a Show Mode on/off to enable Alexa. Mine was on and something happened during the Alexa "training" when it started up automagically. Happened in the first few days of the device (I assume after sw upgrades as well could cause it). I could not even do that until i removed it from my leather case as the lip of the case prevented access to that as it was stuck in landscape mode even. hope that helps others!