iPhone 7 stuck in guided access mode

My iPhone 7 is stuck in guided access mode. Normally I can push the home button 3 times or use touchID to exit, but neither are working.

Things I've tried:

• Holding the power button down. Does nothing
• Holding power & home button down together. Does nothing
• Using touchID to exit guided access mode. Does nothing
• Triple pressing the home button to bring up the passcode menu. Does nothing, no menu comes up.
• Putting my phone in Lost mode from icloud.com. Unfortunately after I put in the password to exit lost mode, guided access mode just resumes.
• Also tried playing a sound from iCloud. Also has no effect.

I'm on an iPhone 7 running iOS 11