hi my iphone decive cant turn off. the slide to power cant slide

Try using this force restart sequence to reset the iPhone: Force restart iPhone - Apple Support

Hello~ Try it this way from a prior post by *Axel Foley*...

(1) Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

Post back if needed and take care.

~Katana-San~