Hi,
if you have tried these then thats all I have.
1) Turn off battery saving mode and reboot.
2) Double check you have not enabled AssistiveTouch feature, if so turn off and reboot.
so far
nothing works. Hard Reboot, reset,
How did you do this? if via the Sleep/Wake and Home buttons, then I would suggest you go through the settings route.
1) Go to your home screen.
2) Open the settings and go to general.
3) From the general section, go to reset.
4) Select erase all contents and settings.
5) If you set a password for your device, make sure to input it and confirm your choice.
6) Allow the whole process to complete.
7)
Restore your data files to your iPhone SE using the backup you have.
Remember doing a hard reset or a factory reset on your iPhone SE will remove everything.