Power + Volume Down is how you get to
! to begin with.
If the phone goes to ! on it's own... You likely have a stuck Volume Down button. If the back is removable, remove it and inspect your button action, see if you can clear it.
Hard Reset is...
Power off the phone > hold Volume Down > press Power > keep holding Volume Down until you see the exclamation
! screen, then immediately release the Volume Down
Now tap Volume Up / Volume Down / Power / Volume Down
You should see the spinning gears and your phone will reflash the last OS version held in recovery. You do lose data, but get your phone back. Sign into your Microsoft Account and restore your backup during the set up.
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