@Shirley_fleming
Check it is charged up or able to be charged.
You may need to check with a different charger.
If all is well there, hold the power button and volume down together for 30 seconds or so until phone vibrates.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion.
This is not Customer Service so we are unable to help with account specific issues.Currently using:
Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)