Hello Someoneplshelpme,
A few things to check, as they may block the ability to use "Hey Siri":
- Go to Settings > Accessibility
- Tap on Siri
- Do you have 'Always Listen for "Hey Siri" enabled here?
- Go to Settings > Accessibility
- Tap on Sound Recognition, is it enabled?
Does this issue occur when the iPhone is connected to a power source, even if not normally required?
What happens if you disable Bluetooth in:
- Go to the Settings app
- Tap on Bluetooth
- Disable Bluetooth
Then test it out. What happens when you attempt to set up "Hey Siri" now? Here's a quick link to set it up: Use Siri on all your Apple devices
Hoping to hear how it goes, take care.