starting problem iPhone SE
While updating to latest IOS the phone stopped, and apart from the apple-symbol nothing happend. I can't turn it on of off, it doesn't react on anything.
iPhone SE
Basics from the manual are restart, reset, restore
User troubleshooting is:
Follow the 3R's- if a restart does not solve your problem proceed
1. restart, ie power off/on,
2. reset http://support.apple.com/kb/HT1430
3. restore from backup, restore as new device. http://support.apple.com/kb/HT1414
Sounds like you might have to restore.
Holding the power button and home button for an extended amount will force a shutdown. Then try restarting as normal— go from there.